Thanks for taking my question about Vagrant Story. And I totally agree with what you both said. In fact, something similar was said this recent video by Playstation Access where he talks about his love for the game, but that a game like this couldn't really exist today: https://www.youtube.com/watch?v=Bg4t9cyHifg It's a great video in case you haven't seen in yet!
There are quite a few similarities between Vagrant Story and the Souls games that go beyond even gameplay. Some locations in the Souls games are based off of real world locations, just as Lea Monde was. I don't know much about Miyazaki and his influences, but if someone said that Demon's Souls (or any other) were influenced in part by Vagrant Story, I'd believe it.