I play for the most part at the end of the week / weekend due to school, so my numbers may be inflated by weekend numbers, but I see a lot of people on Selbina, my screen can only load 40 at a time but hey I see a lot of different 40 people just in Uldah, and if I see more than 20 people in Gridania on my server, thats a good population day for Gridania! I was told by people on Besaid that Besaid population is on par with Selbina if not a little less but who knows, I think its because Besaid and Selbina were "official" w/e servers, like Selbina the JPs wanted it for themselves but XI players worldwide wanted it to, and then the french also said "its the francophone server" so its looking like a weird America from back in the day if Japan was one of the powers also. And Besaid is official RP I heard. I would love to know the exact population I think they said we'll get this when we pay for the game and have the /sea all functions which are pre 2.0 and at the very latest at 2.0. At least this thread tells SE we're still interested in that. I understand though that while the game isn't in its hottest state the people who write articles , basic free marketing, might slam XIV for its numbers and that leads to a vicious cycle worse than now of people not wanting to pick up the game.

http://xivpads.com/ I think has the closest numbers for just people who updated their game for a patch, it doesn't automatically reflect those who play though.