Most news reporters seem to say "Keev," which is a mispronunciation. In Ukrainian, it is more like "Kee-iv." Not a long Keeeee, but a clipped one. Or, Keeyiv. It's hard to write it the way it's pronounced.
That aside, it should be OK to say Kiev. We don't pronounce "Paris" as they would in France, nor do we say Lisboa for Lisbon, etc., etc.
Never mind Firenze or Munchen!