I understand that a lot of restaurants won't be open on a Sunday evening, but since we plan to tour the Marais on Sunday afternoon, is it likely that there may be more dining options open in the Jewish quarter open on a Sunday?
That is what I understood too, before our trip. But, when we were there on Sunday, we didn't have any trouble finding restaurants open. I don't recall in what area we ate, but we had no problem.
A recent post on a similar dining-in-Paris question led us to this website, including lists by neighborhood of restaurants open Sunday and Monday: http://parisbymouth.com/
We haven't tested the reliability, but will be doing so in a few weeks.
I believe RS recommends the Marais for both shopping and dining on Sunday.