Well there has been negligible chances of failure of this news as Game Informer has a track of providing true news to the readers. There has been an image of the game in the magazine along with an article on it where it has been mentioned to come for Pc platform as well. If you have a magazine with you right now, just open it and go to the game's page. There you will see Red Dead Redemption marked for PC platform as well, so this means that the game is coming on PC also.
Well this news about Red Dead Redemption PC version has been confirmed by Game Informer magazine only and not by the Rockstar, the official authority of the game. So we have to wait for more to see an official announcement regarding the Red Dead Redemption PC game. If Rockstar confirms it then watch it releasing simultaneously with the console release, that's my guess. It won't be wrong.