So anywhere probably from 200 - 800k at that point. Cool.
If it had been closer to 800k, I'm sure they would have boasted that ("almost a million", "over half a million!!!111!!!1" or something), given that it would be about 1/4th of the console's install base. Also, "hundreds of thousands of gamers playing Titanfall" is also a strange metric in a sense that it doesn't necessarily mean each and every one of those has a copy of their own. Maybe a lot of those are brothers & sisters, roommates, couples etc. playing on their own accounts, counting for 2-3 separate gamers in some households. Or not, I'm not sure if MS has taken that into account.