I was there. There were more KU fans, but the Norther Iowa fans were very loud. KSU fans were cheering for UNI in a great way, and the KU fans thought every call against them was a bad one. It was a wonderful night.
Generally, it seems like the non-affiliated fans who are just from the area that go to the games seem to root for the underdogs, so my guess would be there were more of the non-KU/KSU/NIU fans rooting for NIU than KU...that just seems to be how it always goes...people like to watch the scrappy underdogs pull off the upset...