What makes you think Barcelona would want Gerrard? They have Xavi, Iniesta, Yaya Toure, Marquez, and Keita who can all fill the central and wide midfield positions. I'm sure if Barcelona are looking for a midfielder right now, it sure as fuck isn't Gerrard.
Also, whilst I'm not a fan of comparing players of differing position and type, Torres is far more important to your club than Gerrard.