According to preliminary data from Nielsen Media Research (final numbers could change, but probably not by much), FNC averaged 5.15 million viewers from 8-11 PM last night. CNN averaged 1.2 million, with MSNBC averaging 1.32 million.
From 10-11PM when the broadcasters had live coverage, FNC averaged 6.89 million viewers, NBC averaged 4.77 million viewers, CBS averaged 3.12 million viewers and ABC averaged 2.86 million viewers. During the same hour CNN and MSNBC each averaged 1.47 million viewers. (Source)