Surprising most of our polled readers, Fringe not only premiered with a 1.9 adults 18-49 rating on its first Friday, but held that rating in its second Friday.
Plenty of our commenters would contend however that tonight is the first real test for the show, going up against first run competition on both CBS (Super Bowl's Greatest Commercials) and the CW (Supernatural). Don't discount SBGC, last season on a Wednesday it drew an impressive 2.8 rating.
Holding that 1.9 rating would maintain Fringe's Renew / Cancel Index prognostication of "more likely to be renewed than cancelled". Ratings much below that, and it's edging into the "toss up" range.