It can definitely be a factor once the voting starts up. Her sister and famous friends can all tweet up a storm to get her extra votes every week. I wouldn't be surprised if Blake factored that stuff in when he picked her.
Assuming Holly Henry makes the live rounds, I suspect Blake will be pushing the rest of his singers off to the side to clear a path for her. Only a handful of contestants have charted on iTunes so far, but Henry blew everyone else out of the water.