In the UFC, contracts are set up so that they get a base amount to show, and another amount, usually double if they win.
I've seen fighters get anywhere from 4K a fight to 500K a fight. The UFC also hands out official bonuses for KO of the night, Sub of the night and Fight of the night, as well as unofficial locker room bonuses for good performances by fighters.
Between those bonuses and the sponsorship money a fighter accrues, it is nearly impossible to determine an exact number.
For some, 3-4 fights a year is barely enough to make a living, while established fighters like GSP, Rampage or Liddell can clear over a million in a night.