I found this website which tracks the player populations for games that appear on the Steam platform, but doesn't limit itself to only Steam accounts. Even daily activity for Twitch and YouTube is included in its metrics.
http://steamspy.com/app/218170
Age of Conan: Unchained - US version
Owners: 151,111 ± 9,394
Players in the last 2 weeks: 2,143 ± 1,119 (1.42%)
Players total: 68,742 ± 6,337 (45.49%)
Peak concurrent players yesterday: 87
I had stated over a year ago that AOC had a total population of about 150k, so this could still be true based on these numbers.