ESPN is located by epcot in the retail area in the Boardwalk resort. ESPN is a sports bar, it is a fun spot for Sunday football games. It will get crowded.
In past years there haven't been any special events for Super Bowl. Obviously ESPN is a big draw for the fan, but expect it to be full by early afternoon.
I've heard the parks are pretty empty on Super Bowl Sunday, so it might be a great time to go if it's not a must. Otherwise, as others said, ESPN Club would be the only place I can think of to watch but get there early!
ESPN will be packed - people will wait in line early just to get in to watch the game. We went over to Big River Brewing instead, which had the game on in the bar. It got crowded, but we were lucky enough to get bar seats. Any resort lounge should be airing the game so there's plenty of places to watch.