Depends on the language but I think in English
Kris reads as feminine and
Chris reads as neutral. I'd initially guess that
Chris is a boy and short for
Christopher, but I wouldn't be confident trying to guess pronouns for someone when all I know is "
Chris" because it could easily be a girl short for
Christina /
Christine /
Christa / etc. or not short for anything.
For
Kris, I'd actually probably use the last name to guess the gender. If the last name looks like it matches a European language that would have a name like
Kristoffer or
Kristian, then I'd be more likely to think masculine or neutral. But if the last name looks English I'd guess that
Kris was a girl and that it was spelled with a K because of a trend.