I'd guess there are at LEAST 10 times as many Giants fans in the UK as there are Rams fans, so in that respect you're right.
However, the saving grace is that most of the crowd will not be bipartisan and are there for the atmosphere and to see some real football.
So that will include plenty of Philly, Skins and Dallas fans as well as those from other teams who don't like the Giants.
My guess is it will be split pretty much down the middle.
And in response to the question about Arsenal fans supporting the Rams. Yikes, no way!
There is nothing either good or bad, but thinking makes it so.