On the PS3 it sold 6mi with 50mi+ active userbase...
Well, let´s look at Tomb Raider DE, if VGchar is accurated, it sold 20% PS3/PS4 and less than 10% 360/XOne.
So, unless Sony push a enourmeous marketing stunt I can´t see TLOU reaching 2mi in the first year.
Titanfall on the other hand will easily reach 4mi by the end of this year.
Edit: Will we have a threat for TF vs every PS4 exclusive? This will became boring soon.