OK. I am basically of 2 minds on the subject. Either almost all of them die or almost none of them die.
If the Night King brings his full force to bear, only a few survive. Either Jon or Danny will live. Either Tyrion or Jaime will live, Either Arya or Sansa will live. The Hound will live to see the Clegane Bowl. Practically everyone else will die. Big Dragon lives.
However, part of me thinks that The Winterfell crew is going to hammer a smaller portion of the army, sans the Night King. We did not see the night King at the end of episode 2.
If I were the Night King, I would pull some Sun Tzu shit and do a head fake to Winterfell while I sent the bulk of my forces to Oldtown. They got no Dragons. They got no Dragon Glass. They got no wildfire. Plus those old Maesters were pretty condescending to Samwell Tarley. They would be essentially helpless and not expecting it. I could wipe out the Citadel, a necessary step to bring about permawinter, and Oldtown is the 2nd most populous city in Westeros. The new undead soldiers I conscript there would be orders of magnitude more in number to the sum I sacrifice at Winterfell.
The only hypothetical problem with this is Oldtown is a fucking hike from where they are at, which would take a little creative license.