It's silly to worry about how many people will view the film as opposed to the debate. There's no way anywhere close to as many people could view it in the theater as the debates.
Let's say there are as many as 500 screens that show this (and it's unlikely anywhere near that high). Even if each of them gets 200 people apiece for each of 2 back to back showings that night, that's still only 200,000 people. Even the CW will get more viewers than that for their airing of the debates (assuming they don't opt for regular programming instead).
If you want to see ET on the big screen, go see it and use that DVR thingy to record the debate.
I swear, some people will find anything to blame on Universal. Hell, my bowling league is still scheduled to play that night, too...