Put some pureed foods on his plate and maybe a small pc of your banana.
Leave it there and let him try on his own.
If he does have a sensory issue, then, you will nedd to get a specialist involved.
With your son just turning one, do many introductions of the solid food and let him try the foods on his own.
If you begin to decrease the bottles, he will probably get hungry.
If he continues to gag after a few months, keep the pediatrician posted.
I have a friend who has a daughter w/ sensory processing --she never ate well. She still doesn't as a teen. Occupational theraphy can help.