I like what you've got started, but you definitely need to work on fleshing out what you have before you work on adding more to the rest of the song. As far as arrangement goes, it really is lacking in terms of similarity to the original. If you're remixing Kefka's theme, I have a real issue with finding much of it in this piece. Is this really Kefka's theme, or is there something else in there? What you've got sounds vaguely familiar, but I can't really place it.
The piece itself is fairly well-done, but I have real issues with the way you're handling the drums. From the kit you're using, it sounds like you're going for more of a rock beat, but your actual drum-work is far too low-energy for a rock beat to work. Add some more snare and hi-hat! With that four hi-hat lead in, I was expecting 1 beat of a hard snare roll followed by a hard rock groove, but what you've got is fairly, well, bland. A good drum track could really spice up this song.