The explanation you have quoted gives all the information you need. The estimated winnings are just that an estimate as it is not possible to know in advance what bets will be placed in the future. The actual payout is a proportion of the total prize pool at the end. Your proportion of the bets placed on the winner are weighted depending on how early you bet.
Can you let us track potential payouts pretty please, maybe updated only once per day or something? I've put a small amount on Liverpool for example, before even they eliminated Barcelona, the early bird multiplier was about 80x and the potential payout was much higher. Now that they are left against Tottenham instead of Ajax, a lot of bets are flowing towards Liverpool although with a lower multiplier. It would be nice to keep track of potential payouts along the way, would be more fun and transparent. It could also be used as a guide to do more informed counter bets. Btw I hope Tottenham wins because I also had put a small amount on them too...