I wouldn't use vinegar, it can just add to the smell.
What's the fabric of your couch? If it's a light colour and colour fast, I would take a solution of hydrogen peroxide and water. Did you blot it up? Then wet down with water and blot again? You can do this a couple times and it can help dilute the urine that's been absorbed. With the peroxide solution, You might want to do a test patch first on the back or an area where you can't see. You could even add a nice cleansing essential oil. I've used a few drops of lavender and rosemary in the mix. It works great on areas where my son's diaper has leaked over night, but that's on a mattress of which I don't care about the colour fading or spotting. Sunlight is great too. After treating the mattress, I've put it out in the sun (that was some months ago, the sun barely rises up here this time of year).
Urine becomes ammonia when exposed to air, that's why it starts to smell worse as time goes by. Ammonia is a base chemical, not a acid chemical, but it can be just as destructive depending on how high it's pH becomes when left. I think that's why people want to treat it with Vinegar because that is on the acid side of the pH meter, but you're not trying to neutralise the pH as much as you are trying to oxidize the odour causing bacteria that grows in such a mess.
Good luck and let us know what you end up using and how it works.