Actually, Infamous hasn't sold more than Titanfall on X1, but Killzone Shadow Fall has more sales than Titanfall on X1, but only slightly. Titanfall on X1 may surpass Shadow Fall in the next week or so... according to global LOL VGChartz figures, but then again there's no other figures out there to say otherwise.
Titanfall is not a Xbox One exclusive.
oh yes yes, it's just an MS exclusive that's not on PS4
No. The game is on PC therefore it is a multiplat. Excluding a platform does not make for an exclusive.