Uhm . . . I wanted to comment on the
hoti clause you all keep mentioning. Yes,
hoti can be translated "because," but that's not really the idea. It is broader than that--if you want to be technical, it can be used in an adverbial, appositional, causal, declarative, epexegitcal, or recitative sense. Y'all are focusing on the causal aspect. The NIV, NASB, and NKJV all take that sense, but the ESV, KJV, and HCSB don't. Personally, I don't think we should take this as causal. It should be taken as declarative. Concerning the declarative:
Wallace wrote:This is a specialized use of the direct object clause after a verb of perception. The hoti clause contains reported speech or thought. This contrasts with hoti recitativum, which involves direct speech. It is a very common use of the hoti clause. When the hoti introduces indirect discourse, it should be translated "that"
From Wallace, GGBB, 456.
As for the Greek, my translation is as follows: "And they all said, 'Are
you, then, the Son of God?' And He says to them, '
You say that I am.'" The bold here captures the emphasis in the Greek. It also shows the "you/you" contrast . . . What actually is going on here is that the Pharisees were attacking Him: "Are you, of all people, the Son of God???" Jesus turns it back on them, "YOU, of all people, are the ones saying it." It's hard to Jesus' emphasis of "you" in English. In Greek, you don't have to supply the person (he/she/it/they/you/etc.). It is built into the verb. So when it is expressed, it is emphatic. But not only that, Jesus places it at the beginning of His reply, doubling up the emphasis (in Greek, word order helps show emphasis rather than meaning, as it does in English).
Anyway, I wouldn't make a big deal out of the present tense of "you say" by rendering it "you are saying" in Jesus' reply. It's very, very common for the gospel authors to use the present tense in both narrative and speech for the purpose of bringing the story to life. We do that every day when we are telling a story. "So I go to the store, and this lady says to me . . ."
In answer, then, to the question, "Is "yes" found in the Greek?" the answer is "No, it is not." What you have to decide is whether or not to take
hoti as causative or declarative. If the former, then translating it, "Yes, because I am" is a good enough translation. If the latter, then that translation would be incorrect.
Hope that helps.