When αυτος is in one of the it is the third person personal pronoun.
καὶ ἠρώτησαν αὐτὸν καὶ εἶπαν αὐτῷ· τί οὖν βαπτίζεις εἰ σὺ οὐκ εἰ ὁ χριστὸς οὐδὲ Ἠλίας οὐδὲ ὁ προφήτης;. (John 1:25)
greek syntax principle 20
When αυτος is in one of the it is the third person personal pronoun.
καὶ ἠρώτησαν αὐτὸν καὶ εἶπαν αὐτῷ· τί οὖν βαπτίζεις εἰ σὺ οὐκ εἰ ὁ χριστὸς οὐδὲ Ἠλίας οὐδὲ ὁ προφήτης;. (John 1:25)