Carl....Apple cider vinegar and a little Dawn dish soap in a small bowel....
that's what I always use!
I remember when I was a child ,Mama would get a bushel of peaches to make Yummy peach preserves... gnats would fill the kitchen come from out of nowhere. We would ask Mama where did they all come from. She would say they love peaches like you do. I do not think she knew But they did come every time she would start canning some kind of fresh vegetables or fruits So clean all the signs of that up. Seems like it takes longer to get rid of them now than it did back then. One year I discovered one of the problems they will build and live in your drains put some kind of strong cleaner in every single drain shower and tub even. Then turn water on in every water valve wash a load of clothes even. That got rid of my problem hadn't one again for two years then the other day my husband left a jar of opened olives on the cabinet and juice where he ate.Then went and got in front of t.v When I went in the kitchen; from out of no where hundreds it seemed still trying to get all them out but we still see a stray now and then .I am watching all my drains till every single one of them is gone.
Sometimes Gnats like to hang around and have a party in drains. Are the gnats only in the kitchen? If not, squirt dish washing detergent down the tub/ shower drains. Also the bathroom sink drains. Carefully pour very hot ( boiling if possible) into the drains. The soap may bubble up . This should get rid of the gnats.
I agree with the first response from tinyshoes. I had the gnats by my front door in the spring. I put the Apple cider vinegar in a glass jar with dawn dish detergent and just left it there. They are attracted to it.