They're interchangeable, at least in terms of the answer you'd give, in the case that you have lived in Kyiv one time and are still living there.
If you've lived there more than once, whether or not you're still living there, "How long have you lived?" requests a total time. If the person still lives in Kyiv, the reply would likely be something like "I've been living here X months/years this time, but I have also lived here previously for Y months/years."
I'd be curious about the proper Ukrainian versions for the multiple-residence-time scenarios: which questions would yield which answers and whether perfective vs. imperfective verbs yield any difference in meaning or are even possible.
In English "How long have you lived in Kyiv?" and "How long have you been living in Kyiv?" mean exactly the same thing. Both should be accepted translations. No disrespect intended, but it might be a good idea to have a native English speaker check through your exercises. The Ukrainian course is full of English mistakes like this.