Is there going to be a 8th gilmore girls season....?

No there is not. There isn't really an explanation. The show ended a few years ago after 1 year on the, then new, CW network and the show wasn't picked up for an 8th season. Sorry, I really wish there was, but I wouldn't believe any rumors that there is. Lauren Grahm is going to be on that new series Parenthood anyway. At least we can see her there :)