It should be fairly higher than Queen's because Oda usually uses bounty as a hypetool and considering he reserved King's Bounty as the last reveal among the calamities, there should be a fair gap compared to the previous reveal(Queen's)
On the other hand though, King and Queen have a closer relationship than with Jack, so based on this, the gap between King and Queen's bounty should be fairly smaller than the one between Queen and Jack
At best then, i could see King's bounty ranging anywhere between 1.4 and 1.5Billions, but it shouldn't be any higher
From the poll however, it's impossible to vote since i don't think it'd exceed 1.5Billions while at the same time thinking it should be in the 1.4Billions range