Well, we don't know that, but german men of jewish faith who had served in WWI where given some kind of "exemption" from some forms of persecution especially earlier and before the onset of the full scale extermination efforts of the Holocaust. For example they were exempted from the law that cast all jews out of public service in April of 1933 (that was changed later though).

I recently saw an example in an exhibition of a jewish man from Hannover, whose name eludes me atm i'm sorry to say, who was married to a christian born woman who had converted prior to their marriage, but reconverted in the 30s when the family felt the pressure on jews rising. When SA men came to their flat during the big pogroms of the 9th of November 1938, she had papers to prove her belonging to the protestant church and her ownership of the flat and the men did not destroy the flat as so many others, but they did take the husband to a KZ as so many other jewish men. He was however released quickly when they found out about his service in WWI. And the family was allowed to continue living in their own flat when jewish families all around had to move to special "jew houses", they weren't deported either, when the deportations started in late 1941, other than his parents for example. In the end though there was some accusation of sabotage against him later in the war by the Gestapo and he was deported to one of the big extermination camps, where he died. His wife and daughter survived though. Of course there are two factors here and the status of his wife might have been worth more than his service and in the end it didn't save him. So not quite the same as Otto Frank, but certainly many jewish men who had served in the imperial German army in WWI did not survive the Holocaust.