According to Dave Meltzer, the finale of The Ultimate Fighter did a 1.4 rating:
The Ultimate Fighter finales drew a 1.4 rating on Saturday night and was number one on television in the timeslot in males 18-49 and males 18-34.
This is significantly lower than the finales for season 5 and 6, but then again those shows had major main events that were promoted for weeks, as opposed to a completely meaningless main event that headlined this show. The most fair comparison is probably to the season 4 finale, which did a 1.1 rating.