From the BBC:
A visitor to the Infinity Mirrors art exhibition in Washington DC has lost his footing, reportedly whilst* taking a selfie, and fallen into one of Yayoi Kusama's signature polka-dot pumpkins…
A similar sculpture sold for almost $784,485 (£635,000) in 2015 according to Artnet.
Seeing as the sculptor is still alive (although getting on a bit), the “value” of the pumpkin depends entirely on the lower of a) how much the owner is prepared to pay for a replacement and b) what she will charge to sprinkle some holy water over a new one and certify it as an original.
What an earlier pumpkin sold for is neither here nor there.
If the owner of the collection of dozens of similar pumpkins decides that it makes no odds whether one is missing, then it's not worth that much; if the set has to consist of some magic number of pumpkins to be considered complete, the price she can charge for a new one is considerably higher etc.
If the artist is dead and there is no possibility of obtaining a new replacement, then the equation is different of course, that's just down to supply and demand between owners and would-be owners.
* “Whilst” can also mean “although”, so the better word to use is ”while”.