I'd guess this depends on region/demographic, but at least in my circles on the west coast, "guys" is gendered when it's used to describe or identify people in the third person, but it's gender-neutral when used to address a group of people in the second person.

So "the guys" or "how many guys" always refers to men, but "you guys" carries no implication of gender at all. I often hear people address groups consisting entirely of women as "guys", and nobody bats an eye.

Which itself seems to be related to the word "guy" as in "guy wire" also related to "guide", "guidance", or "guidelines". Meaning to lead, direct, or conduct. To show the way.