Really it didn't make a difference. Those 47% never voted for Bush either back in '00 and '04. Bush had to run the table on the remaining 53% and he barely squeaked out.
I don't think a Republican is going to win a election anytime soon unless WW3 or some sort breaks out.
I don't know about Romney's numbers. More relevant: McCain carried 45% of votes in 2008. Romney had to get to 50%+. He didn't do it and the "47% comment" hurt.
It's not so much that people dependent on government didn't vote for Romney (or Bush or McCain). It's that the comment made Romney look bad with swing voters.
That's the way it is with a lot of these "gaffes": the people the "gaffe" refers to may not vote for you in any case, but the comment hurts you with other voters who might have been yours to pick up.