According to data collected by Greg Miernicki, a technology professional, Google+ now has more then 2 billion accounts. Google had not made this data public, the techie had himself been tracking this information using third party tools.
However, a Google team member, Mark Traphagen, accepts the accuracy of this data in a post. He also clarified the following misconceptions that might arise among people after seeing this number:
1) These aren’t all “active” accounts. That’s right. And it’s wrong. If by “active” you mean “doing stuff at plus.google.com” you are correct. But see objection #2
2) Non-active accounts aren’t “real” Google+ accounts and shouldn’t be counted. NO <buzzer!> They are only inactive in one small part of Google+. But most of these are active accounts anyway, as far as Google is concerned.
As per the social user stats on Statista, Facebook had 1.3 Billion accounts till second quarter of this year. This might come as a surprise, since the popular notion has always been that Facebook is a more popular social network. The difference in the numbers could be attributed to the fact that Google used to have a mandatory Google+ sign up for its different products. Also, any person having or creating a Gmail account would automatically get enlisted on Google+ as well. Google has recently changed this.