well, there's a difference between "fighters" and "GSP" or "A.SIlva"
it's definitely a "meet somewhere in the middle", classic negociation technique that actually has been proven to work.
He probably has something like 20Mil in his head and will try to settle for as close as 30 as possible.
The important part is the initiation and initial demand, if the UFC responds (likely by the negative), then they engage themselves to the negociation, which will make said negociation easier for GSP's part because of how he will have set the comfortable and workable $50M starting point of the talk. I can imagine the UFC offering 15M, then GSP going down for 40, the UFC offering 20ish, GSP going down for 35, UFC offering 25-30 and GSP saying "ok, I'll do it"
It'll still be 3 or 4 times the usual, and enough to last for a lifetime.