I don't think you realize how many Tech fans there are all over the country who couldn't tell you who the QB is, who the coach is, or their record. And this is the 1 game they want to watch.
And I'm not touting GT here. Michigan and Ohio State have them. USC has them, Florida State has them. There are lots of fans who may never wear a piece of merch, never post on a message board or send a dollar of support. But there is 1 game that is important to them.
I'll also add that it was a good game and the fact uga keeps winning means more fans of other teams keep rooting against them, aka they were watching too. The fact that it was close, GT 100% contributed to those ratings.