If my work permit is cancelled after being fired, does my NON-B visa still remain valid until May 8, 2024?

That stamp in your passport (not a visa but an extension) means nothing once your work permit is canceled. Find out exactly when your employment ends (ie what date will they put on the letter) or perhaps negotiate this date with HR if you're on good terms with them. That will be the day your work permit needs to be canceled as well as your visa extension. Some immigration offices will let you do this in advance (eg Bangkok) while others do not.

For My experienced with a crazy boss I quite and was cancel, and i have to fly out and make a re-entry but It was 4 years ago.

Interesting this got approved @admin I submitted the same question yesterday and was denied with a snarky comment.

It would be cancelled too.

Your extension based on employment is not automatically cancelled, you have to cancel it by yourself. Your extension of stay is invalidated when your work permit is cancelled. Even if you still have your stamp on your passport, you would be overstaying.

Go to get your extension cancelled, leave Thailand and return if you want to have some more time in Thailand.

Nothing will be cancelled. IT is YOU and only YOU who is responsible for the documents to work and life in Thailand.

IF you get fired from the job, get the document from your employer, visit the Ministry of Labor and cancel your Work Permit using the same date as last day of employment. Than you visit your local Immigration Office and cancel with documents from employer and ministry of labor your Extension of Stay permitted up to 8th May 2024 using the same last day of employment.

IF you need some time as you need to leave the country, you might apply for a new Extension of Stay, cost 1.900 Thb and if you can NOT meet any requirement it will be NON APPROVED and you get 7 days to pack your bags and leave Thailand.

I am guessing that you actually have an extension of stay (from immigration) and not a visa. As such, you need to cancel both your work permit and your extension, dated the last day of your employment.