windows I am sure copied some unix ideas. But Unix came out Long before Windows. Linux is just a kinda copy of Unix. I consider it a Unix system, but it is not true system V Unix. It is closer to System VII(BSD(a newer version of Unix))
True Unix is VERY expensive. Who ever sells it Licenses the rights from Bell labs, or I think it is Lucent now.
Bell core turned in Telcordia.