My BIL went through something similar a number of years ago. He did a little job hunting and was actually ready to switch jobs (they say it's easier to find another job when you are employed then when you aren't). His boss caught wind of it and gave him a huge raise. He was pretty much running things for the boss and I think the raise thing was just overlooked. Another ten years or so went by and he was feeling the same way. Then the boss put a percentage of the company in BIL's name (a really small percentage but worth a lot if the company were ever sold).
My suggestion.
If he's willing, have him look around a bit. Maybe there is something else out there. If there is, he has a bargaining chip when he asks for more money.
If he's not willing to do that, he has less of a position, especially if there are "money problems," which sound like hooha, but I've never heard of a company doing well when it comes to bonus and raise time.
I wish him well. He sounds like a great guy.