BTW: (it happened to me yesterday, so it's fresh in my mind R1/R2 double steal - batter interferes with throw to 3rd by stepping backwards out of the box right into where C was stepping forward - easy call).
If the runner is tagged out on the throw, then the interference is ignored and the out stands.
If the batter had not moved and stayed in his position in the box, then there's no interference even if the C makes contact or doesn't attempt the throw. Ironically, ever since Little League days players are "taught" by their coaches to "get out of the box", when in fact it's probably the worst thing to do. The batter cannot move or "re-establish" his position after the C receives the pitch. In a game many years ago I had a batter stay where he was and the C threw the ball somehow glancing off the top of the batter's helmet - oooooh boy was the defensive coach mad that I didn't call interference.