Groban's father is Jewish, but converted to Christianity. I doubt Groban practices Judaism or even identifies as such. I think it's a similar deal for Arielle Jacobs.
If Parade, Funny Girl, Just For Us, and Leopoldstadt were still running, you'd definitley lose a lot of people. But, alas, none of them will be.
There's no way that Guttenberg would be starting performances the day before Rosh Hashannah if it would be a problem for Josh Gad.
With Harmony and French Republic not coming until much later in the Fall, there aren't so many Jewish leads on Broadway right now!