well the ps4 has twice the user base as the bone so................this would be impressive with destiny selling 2x TF numbers or more.
look at it from a percentage stand point.
about 20% of ps4 owners are interested in destiny
and around 40% of xbox 1 owners are interested in Titan fall. so chances are if titan fall was a multi plat, destiny would have a hard time climbing that hill.
what should be compared is xb1 destiny vs xb1 titan fall.
http://imageshack.com/a/img801/6426/f7pc.gif
^Yes that's me ripping it up in the GIF. :)