Titanic's first release gross is $1.8 billion ... so The Force Awakens has beaten that easily already.
If you want to bring up the inflation argument, great ... in that case you have to acknowledge the original Star Wars spanks Titanic and destroys Avatar.
Also TFA was coming off the prequels which were very divisive in their reception, so that did not help TFA. If TFA was the Star Wars movie that had released in 1999 instead of The Phantom Menace ... it likely would have beaten Titanic's record then too. TFA will do it, it will just require a re-release which is fair seeing as how Titanic got one.