What is the biblical basis for believing that Christ is the man upon the throne from Ezekiel 1:26? In Ezekiel 1:26 we read


  And above the firmament that was over their heads was the likeness
  of a throne, as the appearance of a sapphire stone: and upon the
  likeness of the throne was the likeness as the appearance of a man
  above upon it.


My question is: 

What is the biblical basis of those who interpret this as a vision of Christ, the Messiah (himself, not just a figure of him)?

A good answer must take in consideration respected published commentaries.
The included commentaries include references to the following verses, among others (the citations in each have been preserved in this answer).

Daniel 7:13-14 In my vision at night I looked, and there before me was one like a son of man,[a] coming with the clouds of heaven. He approached the Ancient of Days and was led into his presence. 1He was given authority, glory and sovereign power; all nations and peoples of every language worshiped him. His dominion is an everlasting dominion that will not pass away, and his kingdom is one that will never be destroyed.
Rev 1:12-18 NIV I turned around to see the voice that was speaking to me. And when I turned I saw seven golden lampstands, and among the lampstands was someone like a son of man, dressed in a robe reaching down to his feet and with a golden sash around his chest. His feet were like bronze glowing in a furnace, and his voice was like the sound of rushing waters. The hair on his head was white like wool, as white as snow, and his eyes were like blazing fire. In his right hand he held seven stars, and coming out of his mouth was a sharp, double-edged sword. His face was like the sun shining in all its brilliance. When I saw him, I fell at his feet as though dead. Then he placed his right hand on me and said: “Do not be afraid. I am the First and the Last. I am the Living One; I was dead, and now look, I am alive for ever and ever! And I hold the keys of death and Hades.

Since he &quot;was dead,&quot; but is &quot;alive forever&quot; it's clear that this person in the latter verse must be Messiah. Notice the similarity of the description of the person in the verses immediately following Ezekiel 1:26. These commenters found this to be strong biblical support to interpret the vision recorded there as one of Messiah.
Here is Matthew Henry's commentary on Ezekiel 1:26-28

The eternal Son, the second Person in the Trinity, who afterwards took the human nature, is here denoted. The first thing observed was a throne. It is a throne of glory, a throne of grace, a throne of triumph, a throne of government, a throne of judgment. It is good news to men, that the throne above the firmament is filled with One who appears, even there, in the likeness of a man. The throne is surrounded with a rainbow, the well-known emblem of the covenant, representing God's mercy and covenanted love to his people. The fire of God's wrath was breaking out against Jerusalem, but bounds should be set to it; he would look upon the bow, and remember the covenant. All the prophet saw was only to prepare him for what he was to hear. When he fell on his face, he heard the voice of One that spake. God delights to teach the humble. Let sinners, then, humble themselves before him. And let believers think upon his glory, that they may be gradually changed into his image by the Spirit of the Lord.

That Pulpit Commentary agrees that the man alludes to Messiah, if it was not his own appearance, and includes cross references from Daniel:

It is noticeable that this preluding anticipation of the thought of the Incarnation, not recognized in the vision of Moses (Exodus 24:10) or Isaiah (Isaiah 6:1), appears prominently in the two prophets of the exile - here and in the memorable Messianic vision of &quot;One like unto the Son of man&quot; in Daniel 7:13. What might have been perilously anthropomorphic in the early stages of the growth of Israel, when men tended to identify the symbol with the thing symbolized, was now made subservient to the truth which underlies even anthropomorphic thought (comp. Revelation 1:13).

Elliot's commentary briefly includes,

Yet possibly there may be even her a hint at the great truth of the incarnation. (Comp. Daniel 7:13; Revelation 1:13.)

Lastly I'll include the Jamieson-Fausset-Brown Bible Commentary, which is for our purposes the most poignant:


The Godhead appears in the likeness of enthroned humanity, as in Ex 24:10. Besides the &quot;paved work of a sapphire stone, as it were the body of heaven in clearness,&quot; there, we have here the &quot;throne,&quot; and God &quot;as a man,&quot; with the &quot;appearance of fire round about.&quot; This last was a prelude of the incarnation of Messiah, but in His character as Saviour and as Judge (Re 19:11-16). The azure sapphire answers to the color of the sky. As others are called &quot;sons of God,&quot; but He &quot;the Son of God,&quot; so others are called &quot;sons of man&quot; (Eze 2:1, 3), but He &quot;the Son of man&quot; (Mt 16:13), being the embodied representative of humanity and the whole human race; as, on the other hand, He is the representative of &quot;the fulness of the Godhead&quot; (Col 2:9). While the cherubim are movable, the throne above, and Jehovah who moves them, are firmly fixed. It is good news to man, that the throne above is filled by One who even there appears as &quot;a man.&quot;