This week's PS4 launch of Final Fantasy 14: A Realm Reborn helped the MMO pass the 2 million mark for registered accounts. Square Enix didn't reveal any hard figures for how many players are exploring Eorzea on PS4, but we know six months ago the number of registered accounts was at 1.5 million. Meanwhile, a trailer from February proclaimed the second-iteration MMO had "over 1.8 million adventurers."
It's worth noting registrations do not equate to active subscribers, although the base game does require a purchase. According to a translated 4Gamer interview with Director Naoki Yoshida, in March around 500,000 people were logging into A Realm Reborn each day.