I've heard arguments both for and against and I'm not firmly in either camp. It's definitely not a direct cause and effect - if your horse is stabled near a cribber it will become a cribber. If that were true, they'd be a lot more cribbers, because most larger boarder facilities have at least one or two.
What is true, I think, is if your horse is already nervous and/or bored, and is stabled next to another nervous/bored horse, then he's likely to pick up the habit or any other stable vice.
If your horse is content and laidback and likes his routine, I doubt that it will affect him.