Explainer / John
John 8:58
Yeshua said to them, Truly, truly, I say to you, Before Abraham was born, I am.
Ἀμὴν ἀμὴν λέγω ὑμῖν, πρὶν Ἀβραὰμ γενέσθαι ἐγὼ εἰμί.
We kept the ASV's wording, in modern English: "Before Abraham was born, I am."
Why
The verb
εἰμί is present tense, first person: "I am." This version prints the present as the Greek has it.
The phrase elsewhere
ἐγώ εἰμι is ordinary Greek for "I am" or "I am he." The healed blind man says the same words in the next chapter (9:9, "I am he").
More
The Septuagint uses ἐγώ εἰμι where Yehovah speaks in Isa 43:10 and 46:4.
Exod 3:14
The Hebrew is אֶהְיֶה אֲשֶׁר אֶהְיֶה, "I will be what I will be." The Septuagint there reads ἐγώ εἰμι ὁ ὤν, "I am the one who is," and the name given to Moses is ὁ ὤν.
"Before Abraham was born, I am" (ASV and most versions); "Before Abraham was born, I have been" / "I existed" (Moffatt and some others, taking εἰμί as a present covering past time); "Before Abraham comes to be, I am he" (taking γενέσθαι with a future sense).