When tackled on the subject of Amy Ponds speculated demise in series 6, Steven Moffat had this to say....
"In the old series, they did off a couple of them. I'm not saying we'll never do it, but it's not that kind of a show.
It's not gritty. It's kind of a lovely, life-affirming, optimistic show without a cynical bone in its body. It's almost odd when you see it in competition with things like Battlestar Galactica, and you think, 'Well that's not us at all.' We're the story of a wonderful man from space who can travel in a telephone box! But I'm not guaranteeing I won't kill someone in the future!"