There was a court case over this. The court found that it wasn’t true that DS9 was based on Stryczynski’s pitch.
I was at a con in the early 90s shortly after DS9 had its first season. Rick Sternbach came out. He did an entire slide show of all the production design evidence they’d submitted to the court. They’d working on developing models for a space station for a show for a long time before. He had huge numbers of drawings. The big thing was the decision to switch from a Federation built mushroom shaped station to an alien design.