Avatar made $760 million in North America and $2.0 billion in foreign box office.
The Force Awakens has already made $363 million domestically after 6 days and should have $560 million after 10 days in theaters (at the end of its second weekend).
The foreign box office is about 10% higher than the domestic run rate and Star Wars has not opened in China.
Star Wars the Force Awakens could have $1.1 billion in North America (over 50% higher than Avatar) and $1.5 billion in foreign box office and still come up short of Avatar's global $2.7 billion. The $1.5 billion would match the second largest international box office which is achieved by Titanic.
$1.5 billion would be $1.2 billion and $300 million in China.