Sponsorship money is a lot harder to get now than a few years ago, for obvious reasons. Top top guys are still doing very well, but bottom guys it's a lot harder.
As far as a percentage of revenue, UFC fighters are lower as a whole than most athletes in the unionized sports. They are higher than WWE performers, though. WWE performers are in the 10-12% range in total. UFC isn't high by any means, but when you have people using the less than 10% based on the announced athletic commission figures, they are either stupid or being intentionally dishonest. There have been main events where the two guys in the main event alone have gotten more than 15% of the total revenue including PPV cuts. In Lesnar vs. Couture, the two guys alone were around 16% not including the undercard guys.