My guess is $9800 until the final.
there is two things wrong with this speculation.
first is the fact that the World Cup has already begun and we have not seen any change in bitcoin price that can be noticeable enough so that we can associate it with this and say this speculation was right.
second is the fact that there are a lot of ways to gamble on these games that are more legal. the problem is online gambling is illegal in many countries and people are used to normal ways of doing it with fiat which are also legal. if they want to use bitcoin they also have to gamble illegally in many jurisdictions and also go through the hassle of buying bitcoin which is signing up on an exchange, verifying account, installing a wallet, learning how to use bitcoin,.... so they won't do it!