I don't think the video game industry matters enough for it to make a significant impact on congress. The only way congress and the rest of the world would pay attention is if google closed down for a day. And that will never happen.
I don't think you should take into account whether or not the game industry matters, I think it's the same as voting, it still counts. We may not be the most significant part of the movement against SOPA and PIPA but if everyone thought that then their wouldn't be as strong a movement there is against SOPA or PIPA, hell there mightn't of even been a movement at all.