A glass polish, like Carpro Ceriglass and a small glass polishing pad, like Lake Country glass cutting pad are your best bet, but I have never tried this on "gorilla" type glass - only on automotive glass.
Bear in mind that doing this by hand will require a LOT of patience and, if you can "feel" the scratch when running your finger or nail gently over the screen, then the scratch is too deep and you won't be able to achieve much.