55,000 gifter dies before 5 years

If a grandparent gives 55,000 this year to a 529 for a grandchild and the dies next year, will 33,000 be considered part of the estate?

Yes, that's how it works. The main advantage of making the gift all at once is that all the earnings are also removed from the estate.
Kris Davis
Kiplinger's Personal Finance Magazine