Most likely the guy will be more than happy to date you but there's a good chance he just wants you for sex sooooo, kinda depends on how you feel and what you are actually looking for- hook up/serious relationship/sex?
The gap itself is maybe the max I would ever support (more like 5 years but whatev) but you are younger so gaps are more serious until you are older like in the 30's cause then it doesn't mean much cause you should both be adults by then. Like I said, all based off of what you want, what you are comfortable with, and if you truly want to date a guy 6 years older than you at this age/time in life
Six years is barely an age gap to me. I think if you're almost 20 there's nothing wrong with it. My sugar daddy is 37, if a 37 year old has an interest in dating me (and we have loads in common) then you'll have no problem dating a 25 year old :)