The Doctor is a pretty smart guy and he has certainly been around for a while. That being said, he’s really not much of a fighter. Kiva’s speed and strength are at a very high level and he should e able to easily get in close and win with a critical slash from his fire blade. The Doctor has no real defense options at his disposal that will stop Kiva for long and forget about offensive options. Kiva also has powered up forms that he could use if necessary. Kiva wins.