Need to visit your spouse once or twice a year even if it's just a short amount of time, showing you guys are traveling together. money transfer to support, having a credit card with their name on it, opening a joint bank account in their country, etc...
You'll get a NOIR from USCIS in about 6-10 months. Then you have 30 days to submit all the documentation back to them for review.
How many interviews did he do before getting the revoke?