Firstly , Kitty is barely getting votes , and going first and singing a song which didn't stand out amongst the others will almost certainly land her in the bottom 2. Not all acts get a rebound vote , Katie last year for example. She only got the rebound vote when a) she performed last/late on the show and b) when there were about 8-9 other terrible acts on the night. And even she finished 7th.
If it was Misha and Little Mix in the bottom 2 , Misha is more likely to go. One of the girls has to go soon and Misha is the most likely as she's been in the bottom 2 already and there's 3 acts in her category, whereas Little Mix have never been in the bottom 2 and are the last group standing.