Bonjour!
Thank you so much for your question and I am really sorry that I have not replied sooner. The stairs are original and they are beautiful. I'm afraid I don't know anyone who makes them now. It would involve various disciplines from iron work for the railings, to stone masonry. My suggestion would be to keep a look out at large scale architectural salvage companies, like Lassco in the Uk and they might be be to help you. Good luck!