While you probably won't be able to stop the occasional scratch from
jumping on/off the sofa (as far as I'm concerned it gives leather a
live-in look, which I like), you can prevent actual scratching by using
Feliway. They sell it a most pet stores and it's a bit expensive, but
worth it. It's a synthetic feline facial pheromone that will prevent
scratching and spraying. Training is also a good idea. Our cats respond
to "No!" very well, but you can use a water bottle as an aid. Also
remember to provide plenty of scratching posts of various textures (our
cats prefer sissal rope) and give positive reinforcement ("Good kitty!")
when he uses them.
Good luck!

buy a roll of sheet plastic.  When you are not there, cover the sofa.
I did this many years ago and the cat learned not to bother my silk
sofa.

I still use plastic on my couch
and it has worked so far.
Good luck!----Perky1

Keep the old sofa around for her to scratch on?? :) if the cat has something
it likes to scratch, something tall and stable.. and when I mean tall I mean
at least to your hip if not higher, then chances are it will leave your
couch alone.    On the whole my five only use the scratching post/tree,
except my old girl who can't stand up, she uses my carpet.. Im fine with
that.  On occasion two of mine will try to scent MY chair.. the one I sit in
all the time.. I know they are only scenting, but it still involves the
claws coming out, so I discourage it., and my chair still looks good.