They are theoretically still in, of course. But their chances are small. It doesn't matter with how many goals will Argentina beat Greece. They only need to beat Greece. After that it's all in Nigeria's hands and in order to qualify they will have to beat Korea by 2 goals difference or more. Could happen, but slim chances for that. With this defense the Nigerians have, the fast Koreans will always find spaces. Korea can play more defensively and bet on counters. They can even allow a 1 goal difference defeat. It's gonna be tough to break such a team and beat it by 2.