Marketing deals aren't gonna help XB1. Unless they give those games away for free with their console like they did with AC: U.
marketing deals arent just about pushing sales for the console at the games launch. they are more about mind share and bran recognition among consumers. if you had the PS4 logo after EVERY game, then that would mean less peolpe would be aware of the XB1 and would think of it less when thinking about buying a game. but when you got half the games having xb1 and the other half PS4. it builds up awareness. so even if the witcher 3 doesnt sell as much on the XB1 than it does on the PS4, these types of deals still help the XB1.