Certainly I think there is less expectation for the Cowboys to win against a GB team at Lambaeu. Because of that there is naturally less pressure by the very definition of expectation. That does not mean that the goals and desires of the team is any different, any less then before.
Personally I expect players to feel more comfortable on the whole when pressure is not on their mind and they can focus on the game and only the game ; not the reactions of the outside world that inevitably creeps in at times. On the other hand, some players can thrive under those conditions.
I think the lowered expectations at this point from places outside the team could help the Cowboys. I also think the uproar caused by the officiating will give the Cowboys an extra edge. I'm certain the players feel they absolutely earned the win versus the Lions 100% (and rightfully so) while many are discrediting it because of the PI call. It might give them an extra edge when they go to Green Bay.