How many positions does a GM analyze before making a move? From a research paper:
Chess players search highly selectively. It is rare that they analyze more than
one hundred positions in the search tree before choosing a move.

In the middle game how many positions does a GM analyze before making a move? What are typical limits of top players?
Of course this depends on the position at hand, but generally speaking...

I am not a GM, but 100 positions (not moves) seems highly exaggerated, though this might depend on your definition of "position" and "analyze".

If you really mean unique (and not only slightly different) positions, and if you mean by analyze, the   full process of evaluating the position, I would guess that the number is between 0 and 3 or so.

Only rarely you would want to calculate  forced line and would have to analyze a position in the future anyway. Most decision making is based on well 
known plans, that follow from the current position on the board.