According to VGChartz for the first week of release in the US Titanfall sold 580,521 copies. VGChartz usually includes copies sold through hardware bundles but not copies bought digitally.
Also for that week XB1 vs PS4 sold 113,549 vs 50,705 in the NA and 30,245 vs 36,978 in Europe and 0 vs 29,734 in Japan

.
So my guess is MS isn't bragging about sales because it's not earth shattering and it's most likely they haven't broken 1 million copies worldwide yet at least on the XB1.