A girl I met online says the travel agency she went to says she can't get a B2 visa to the US because she took a loan out to pay for her trip. Under Russian law she has to pay back a 680 US dollar loan to get the visa. She says the US embassy won't let her get an interview for the visa. Is this a scam? It sounds fishy to me. Can she get a visa and leave Russia?
Do not continue speaking to this girl - she is a complete and utter fraud!
US visas are issued in accordance with American, not Russian, law, which is why her issues with Russian authorities are out of scope for this procedure (unless of course it's a criminal record).
If she hasn't implied it yet, I can tell you she's looking for you to pay her these 680 dollars, after which she'll either keep asking for more for other made-up reasons, or disappear entirely.