They are Russian. Outside of Russia, they are Russians. They are just not ethnic Russians, but are russian citizens. In United States, we have italians, indians, and africans, they are all american. It really just depends on how you classify the term "russian". I can tell you that to an english speaker, they are just russians.
As far as the fight itself, Zabit stands a good chance of winning this one. He does have one potential problem that I can see being a downfall sometime in the future. He tends to miss punches, and allows his opponents to touch him more than he should, his defense lacks in some areas and a good boxer will get through his defense a lot. So whenever someone with a lot of power comes aboard and has good boxing, Zabit will be in trouble. Fortunately, I don't think Brian or even Max Holloway have the power to knock him out with one punch.