keplertracker people on flyertalk report that yes, Marriott will still send you a link to claim the elite night credit on your bday, as long as you have bday in your profile. It looks like it goes in your MR account instantly after you "claim" it by clicking on link they send you. Good luck and happy bday!
Here's what I found out why my elite one night birthday credit never showed.
You have to do two things:
1) Input your birthday into your MR profile
2) You must opt-in and allow Marriott to email your offers. The elite night credit (ENC) comes as an email link. So if you opt-out of spam emails, you won't get the email - hence no ENC. And if you opt-out and your birthday passes, then here's what you need to do.
I've DM via Twitter @Marriott and their technical team is going to attempt to post the missing one night. Good luck on everyone getting their +1 ENC on their special day.
Hope that helps follow members!