How can I cover up cat scratches on wall paper?

Furniture.

I have the same issue. They have scratched, furniture, bar stools, molding on the doors etc

need more details on the paper or a pic

Carefully paint the areas to match.

You could try filling in the cat scratches with some spackling putty and then wiping it down/smoothing it out to expose the surrounding wallpaper while it is still wet enough to do so. Just use a slightly wet cloth or a damp sponge. You could try carefully covering the dry spackling with paint. Hopefully you don't have to match a pattern. I am assuming that the dry wall under the wallpaper is damaged as those car claws are destructive!