The form of the question indicates the confident expectation of an affirmative answer. It is almost an affirmation, you surely believe; you (σὺ, emphatic) who have born such bold testimony to me that they have cast you out. Note the phrase, πιστεύεις εἰς, believe on, and see on Joh 1:12.
Son of God
Both Tischendorf and Westcott and Hort read Son of man.