I'd be glad to help if I can = willing to help if possible, also this sounds like an offer to help 'I'd be glad if I can help' is not grammatically correct, it should be 'I'd be glad if I could help' or 'I'll be glad if I can help': I'd be glad if I could help = he/she cannot help but wants to help. I'll be glad if I can help = he/she wants to help with something upcoming

I think Jeff has that backwards. "I'd be glad to help if I can" means that you want to help, but are not sure if you can. "I'd be glad if I can help" simply means that it would make you happy to help". They are VERY similar, but the first one is less assuming that they are able to help than the second one.

Nope. The first means you have the ability to help. The second means that you MAY not be able to help but will try.

My answer would be yes. However, I think the two sentences have a different "feeling." Grammatically, they are right. But the second one sounds more uncomfortable than the first one to me. Perhaps that is just my experience. The more polite way to say this is the first sentence.