Hello, i am a us citizen engages a Russian girl. Am i eligible for a Russian citizenship?

If you are asking whether u can acquire Russian citizenship if u are a US citizen and marry a lady from Russia, that would be an issue of Russian law. Perhaps u should call a Russian Consulate here in the states and inquire about that.   If you marry your Russian friend, then under immigration law, you can sponsor her for a green card here (without foreign Consulate processing) and as long as she entered the country legally, she can receive her lawful permanent residency.