According to this article, the Earth can support 13.4 Billion people. But this is just somebody’s opinion – from the year 1679. The article mentions 65 different estimates, ranging from 1 Billion to 1 Trillion.
I read in college that the Earth should easily be able to support 50 Billion people. I believe this.
But most believable experts say that the Earth’s population will level off at about 9 Billion, and not really increase from there.
But the article has a lot more information, so read it. If you don’t then you are poop.