In terms of money, maybe. But Avatar hasn't had nearly the impact that A New Hope did. You don't see many people quoting Avatar, or cosplaying, or making fan communities dedicated to using the film as a medium for bettering the world. Star Wars is so engrained in pop culture and the only thing comparable-and I may get flak for saying this-is Harry Potter, but even that doesn't touch the Wars. Maybe Avatar would reach that level with the release of the subsequent films, but I doubt it. It lacks a mythical and spiritual element that binds the viewer to the film and makes it more than just a movie but an experience in of itself.