From a 2014 jewishweek.timesofisrael.com article on the matter:
"The final piece in this puzzle is “Batwoman” #25, written by Marc Andreyko and released a few months ago. In it, Kane talks to Bruce Wayne, and mentions that they’re first cousins. That would make his mother her paternal aunt, so if Kane’s father is Jewish, so was Martha. And if Martha is Jewish, that makes Batman Jewish by strict halachic standards.
Last week, comics journalist Alex Jaffe noticed this concurrence, and outlined it on his Tumblr, but it hasn’t picked up much traction. It’s likely because the odds that the folks at DC realized what they were doing was very, very small.
As Tumblr user Arielle posted on her blog (sic), “i dont want to have to dig through implications implied by other implications and layers of reading comprehension for a mere shred of maybe representation and give dc a pat on the back for it. if he’s jewish they better say he’s jewish outright im not here to grasp at straws im a jew who wants explicit representation.”
Excellent point, Arielle. And there’s also the unavoidable fact that the grave Kate Kane overlooks in the comic in question is unmistakably cross-shaped. “Batwoman” is a series in DC Comics’ total overhaul of its publications known as the “New 52,” and perhaps even Batwoman's Jewishness has fallen by the wayside."
This is a nothingburger.
Bruce Wayne is not Jewish. DC has never confirmed this and likely weren't even aware of the strict halachic standards at the time they made the connection with Kate.
It's 2017, and likely 2019 by wedding time. DC gets zero credit for merely suggesting in a figure-it-out-yourself way that Bruce Wayne may be Jewish. Nope. If Bruce Wayne is Jewish, show me where he even acknowledges on-panel or in any other medium. If he hasn't, then it doesn't exist for him as a character.
Because as it stands, Bruce is ethnically more Scottish than anything (back to Robert the Bruce) and religiously fonder of hanging around Christian imagery. Hell, look at BATMAN FOREVER's flashback funeral: the priest is chanting a Roman Catholic prayer over Thomas and Martha's caskets.
If I had to guess which of the major religions Bruce Wayne was raised as (he's definitely not practicing anything as an adult), it would be pre-Vatican II Roman Catholic.
Again, all this is a long-winded way to say this is a nothingburger.
Bruce Wayne officially being Jewish would be a media bombshell (one that Fox News would explode over). Nary a peep. They're not making any changes of this magnitude to their #1 moneymaker. Sorry.