How far was Peter from Jesus when he denied him? In The Gospel of Luke it says:


  Luke 22: 61- and the Lord turned and looked upon Peter. And Peter remembered the word of the Lord, how he had said to him, Before the cock crow, thou shalt deny me thrice


Was Jesus next to him? In films I've seen, it portrayed as such that Jesus walks by arrested or is next to him (or within viewing range) that Peter sees him and breaks down in tears. Or was Peter able to see Jesus wherever he was at this point? Luke is the only gospel to mention he "looked upon" him.
The Bible says "looked upon" not "looked on" . Looked upon however was used in 1 John 1:1 which could mean something more heavenly..but a few other verses don't seem to match this meaning. Such as Mark 16:17. In fact looked upon is not used much at all, even by Jesus.
Proximity


  (Luk 22:54) Then took they him, and led him, and brought him into the high priest's house. And Peter followed afar off. 


This is the question. He followed, from some distance. 


  (Luk 22:55) And when they had kindled a fire in the midst of the hall, and were set down together, Peter sat down among them. 


The gap is narrowed here. What was the occasion of the fire, the crowd, the spectacle, and Peter with them? Here we are, with Peter, and they, in the midst of the hall. This passage is dedicated to Peter's denial, and his second, and his third; the crow of the cock, which had to come.


  The Lord turned (strapheis ho kurios). Second aorist passive participle of strephō, coming verb. Graphic picture drawn by Luke alone (Robertson). 
  
  G4762
  στρέφω
  strephō
  stref'-o
  Strengthened from the base of G5157; to twist, that is, turn quite around or reverse (literally or figuratively): - convert, turn ((again, back again, self, self about), Strong).
  
  Looked upon Peter (eneblepsen tōi Petrōi). Ingressive aorist active indicative of enblepō, an old and vivid verb, to glance at (Robertson). 
  
  ἐμβλέπω
  emblepō
  em-blep'-o
  From G1722 and G991; to look on, that is, (relatively) to observe fixedly, or (absolutely) to discern clearly: - behold, gaze up, look upon, (could) see (Strong). 


Luke is the only one who gives this account, and in such a way, as it is meant, to convey personal affectation; real in this case. The wording is deliberate, in other words. It would be unnatural, and strenuous, to attempt to interpret this, in any way, other than cause and effect. 

I agree, as the comment, I see above, that Jesus knew all things. However, Peter did not. Though Jesus told him beforehand, he would learn his heart like we all do; in the trial of our determination.

He "looked back" on Peter; also how Tertullian reads it, making allusion to this, in terms of a sudden awakening, of that knowledge of sin to be repented of. 


  "...the occasion indeed demands that I should note down; but (to do so) may seem to be unnecessary. For when the Lord is known, our spirit, having been” looked back upon” by its own Author, emerges unbidden into the knowledge of the truth (Tertullian On Repentance: Ante-Nicene Fathers Vol 3." 


How close? Close enough to meet each others eyes. Close enough that Jesus was able to hear the denial? We know that Peter was in the court. Verse sixty-two says that he went (escaped), out (outside, of doors), and wept bitterly. (The morpho. analys. are taking up more room than I would like. I will supply them @ req.).

Mark 11:11? Because, I see no relation in this to Mark 16:17, but 11:11 he looked round upon, different; and 1 John 1:1 


  θεάομαι
  theaomai
  theh-ah'-om-ahee
  A prolonged form of a primary verb; to look closely at, that is, (by implication) to perceive (literally or figuratively); by extension to visit: - behold, look (upon), see. Compare G3700 (Strong). 


Also different. I feel like Tertullian captured it, in a separate, though not unrelated, context. In an almost mystical, naked, and revealing sense. 

Conclusion

It may be conjecture, but, Peter was close enough to hear, to be heard, and to be seen.


  
  Robertson, Archibald T. Word Pictures in the New Testament Published in 1930-1933; public domain. See Luke 22:61 this commentary. 
  Strong, James. S.T.D., LL.D., 1890. W/TVM