I hope the vinegar spray worked for you, but in my experience working with a professional upholstery cleaning company, cat urine is THE most difficult smell to get rid of. Even with massive commercial deordorizing efforts, sometimes the only way to get rid of the odor is to replace the inner cushion. The petroleum-based fibers hold onto the chemical compounds from the urea like nobody's business!
If you would like us to try to clean it and deodorize it after you have tried your other methods, please contact me. Otherwise, the best bet would be to contact the manufacturer of your sofa to order a new foam insert. If you think this will be a problem in the future, Fiber-Seal is a process that reduces the absorbency rate of the fibers, so you have time to blot up spills. It won't completely protect against the urine going into the cushion, but will help keep the entire amount going deep inside the layers. Good luck!