Nothing is immune to cat claws (except maybe actual rock, but that doesn’t make for nice couch cushions). Instead, provide your cat with plenty of other things to scratch in the same room. Different cats love different methods of scratching, so it may take some observing and trial/error to find out what your cat likes best.
I’ve had a lot success with corrugated cardboard scratchers. They’re inexpensive, last a good while, and can be recycled when spent. A lot of them come with catnip as a scent incentive. Place them where your cat spends the most time. Easy access is key!
Vertical scratch poles, usually with thick rope or carpet, are also great options. This would be a great option as part of a cat perch. Placing it next to your couch will help encourage the cat to use the perch (and thus the scratch post) instead of your couch.
You may also find that there are certain fabrics the cat likes or doesn’t like. It’s never guaranteed of course, but the more texture a fabric has, the more of a claw magnet it is (think rough tree bark vs a plastic fence post).