His ethnicity is not clearly stated in the games dialog. However, if I remember correctly, many of his storyline sequences have clearly 'russia' inspired backgrounds. Its been a rather long time since I played the game through. I believe also that his superior is referred to as a 'komissar' [spelling?] in the dialog, also suggesting a 'russia' like culture.
While he may well be ethnic, I doubt extremely strongly that he is black.
There's really no connection to anything Russian in him beyond his name; his commander, Gabriel, is referred to either by name, or as "Commander".
As for ethnicity... who can say? He and the other former slave workers of Zepp are genetically engineered humans. The dark skin may be intentional, it may be something they acquire after years of labor under the sun, or it may be something else altogether.
