Is it normal for the gum area on top of a tori on palate to become pink and a little swollen after burning roof of mouth? how long until gum goes down

Yes: Trauma of any type can cause inflammation around the palatal tori and thus make it swollen. Resolution will generaly occur within a few days as long as no further irritation occurs.

Normal: For tissues in that area to swell and get inflamed after a burn, like pizza burn , the roof of the mouth gets inflamed and swell up. Maintain good oral hygiene and use antiseptic mouth rinses ,it should resolve within few days.

Pain is never normal: The damage is done, the too-hot food has been consumed, and your burned mouth is swollen. Avoid sharp, crunchy foods, vitamin E application and good oral hygiene will heal the condition in seven days. Take care.