well, i've mostly seen it used as a girls' name but i guess it could be used a a guys' as well =u=
other people named Yuki
-Yuki Nagato (The Melancholy of Haruhi Suzumiya)
-Yuki Cross (Vampire Knight)
Not Necessarily..Yuki is unisex name (that means the name is given to both boys and girls)..while Yuki is a common it might be given to more females than males in anime it seems anyway doesn't make it solely a female's name.