If the Eagles win, then the Rams benefit regardless of how the Rams-Cards game comes out.
If the Seahawks win and the Rams lose, the Seahawks will take the division lead.
But the best of all outcomes, and what is really the most likely outcome (Vegas has the Eagles as 5 point favorites and the Rams as 7 point favorites), is that both the Eagles and the Rams win, essentially ending any hope of the Cards to make the post season and it puts the Rams 2 full games up on the Seahawks. With that scenario, the pressure is far less on the Rams when they play the Seahawks. They could afford to lose that game and still remain ahead in the division and likely ultimately win the division.