At the moment we know little about the popularity of any of the remaining celebs except we know that for the past two weeks, Ricky G's vote has not been high enough to counteract his judges' scores. We also know that Ali and Jade have been in a dance off but that this hasn't happened for two or three weeks. In Ali's case, her position on the leaderboard may have helped preserve her from the dance off. Jade, however, I think has done a Jodie from last year and won over the public. I think her popularity was riding pretty high before the injury (although that may be academic now).
As to the others, who knows where they rank. There's been an unconfirmed report that Chris is well ahead and this seems quite feasilible but we don't actually know. We have even less on the likes of Natalie and Laila except that in reverse to Ricky G, their vote has been high enough to counteract mediocre/low judges' scores (same with Chris).
Of Ricky W we know absolutely nothing except that he's popular enough to, thus far, have avoided a "fall from grace".
There has been speculation that Ali and Ricky W aren't popular. All we have in support of this is Ali's place in the dance off three weeks ago and comments on message boards. Hardly conclusive. They will almost certainly take the top two positions on the leaderboard for as long as they both remain in from now on (assuming Jade doesn't return). If so, it's quite possible that they will avoid a dance off against each other before the final and thus, will both make it through.
If this happens (and I think it's very possible), I don't see Natalie making it to the final. I think Chris's vote is stronger. In any case, I think Chris is Natalie's main competition for a final place.