That is debatable. Michigan has had the most fans in a stadium in a game, and there are fans growing everyday.
Michigan State Spartans
Florida Gators from the University of Florida
The University of Michigan Wolverines have 25 undefeated seasons.
The University of Alabama and the University of Oklahoma are tied for the most with 30 ten-win seasons. This is including the 2009 season.
30 - Florida State