Jenna-Louise Coleman has confirmed in interviews that she would be back for Series 8, but as of yet there have been no details on when the series will be broadcast. With filming of this year's Christmas special not starting till September 2013, it seemed 2014 would have been the earliest date.
However, Coleman said in an interview with The Mirror:
"There could be a big gap until the next series.
I think the writer Steven Moffat is off doing Sherlock and there’ll be a lot of preparation for the 50th anniversary special."
Moffat himself stated in an interview that he had "started planning" Series 8, but in an interview with Entertainment Weekly, he admitted the show is "knackering work" and that he is "statistically nearer the end than the beginning" with regards to his time on the show. He added:
"I just take it a year at a time. I think the feeling of it being done for you is quite unambiguous when it suddenly arrives."