Is red dead redemption the sequel to red dead revolver?

No. It is based on the same models and method of gameplay, but its story does not connect with that of Red Dead Revolver.

The call it a spiritual successor when a game does not directly build on the storyline, but features many of the same elements (see related link) to the 2004 Red Dead Revolver PS2 and Xbox game See related link

Red Dead Redemption is set in the same "world" as revolver but not in the same "area" as none of the towns/locations match. However, when you sit at a campfire in Redemption you will often hear a story about the previous game's main character 'Red' and some of the stories and missions that he got involved with.