Board Thread:General Discussion/@comment-99.240.168.151-20161203065156/@comment-26397825-20161203070005

Not yet. One fellow tried estimating the size of Vale based on its relative size to the rest of Remnant and assuming that Remnant was the same size as Earth, which put the population of Vale alone in the high billions and said that the city was the size of Egypt.

You can basically say that the population of Remnant is roughly the population of the entirety of the United States and get away with it if you really wanted it for a fanfic, but for now we have no way of knowing or guessing.