Does having an acceptance letter from an accelerator increase your chances of getting a global promise?

Hi,

I got accepted into one of the incubators that help fasten the review of your global promise.
I know that officially having an acceptance letter from an accelerator only speeds up the progress. But, in reality will it increase my chances?
I’ve already gotten one rejection (before the accelerator) and worked on improving my evidence. Do many people with the letter still get rejected?

Yes having a letter will just expedite, it doesn’t affect chances significantly. You need to have a strong application irrespective of the letter.