First off look at what I was responding to, a claim that the James Cameron brand was bigger than Star Wars, it aint no director is not even Spielberg. The fact of the matter is that Avatar for all the money it made was no where near the cultural phenomenon that ANH was. The major reason for this and why no movie may ever carry the widespread and deeply felt impact that Star Wars does is pretty much the first thing you see "A long time ago in a galaxy far far away" this moves the classic hero with 1,000 faces from the realm of the impossible that the old myths of Hercules, King Arthur, Gilgamesh etc etc reside in, to the realm of the possible by taking it out of our own world or even galaxy. It allows us to drop some of our skepticism and at some level view it through a similar lens as our ancestors viewed the old myths.
Avatar is a great in theater experience in fact more than any film it has to be seen in the theater to be fully appreciated, this however is also why it doesn't carry the same cultural weight as even other Cameron films like Titanic and T1 & 2, because unlike those films and Star Wars I cannot come close to replicating the in theater experience in my living room with Avatar and this explains why for all the money it made the impact of Avatar recedes more over time than most other major blockbusters, the gulf between the in theater and at home experience is just too pronounced.