Poor Charlie, you and the couch! I don't have experience with this, sorry, but I have heard about people talk about dogs regressing and have incontinence issues after being spay/neutered.
I'm sure he didn't do it intentionally and he will regain his bladder control soon, or was it an intentional peeing? Either way - about the smell, what do the cleaning instructions say on the other side of one of the cushions? Do you have a spot bot? That's the worst. Good luck with everything. Sorry I couldn't be of more help.