The World Cup market-data page now includes the market-prices for getting to each round. These will update in real-time as games progress, but a few things:
1) Round of Sixteen: Uruguay 50% over Portugal 50%, France 59% over Argentina 41%, Brazil 79% over Mexico 21%, Belgium 85% over Japan 15%, Spain 78% over Russia 22%, Croatia 69% over Denmark 31%, Switzerland 54% over Sweden 46%, England 63% over Colombia 37%.
2) Quarterfinals: while Belgium is heavily favored to beat Japan, they are going to be underdogs against Brazil (if they meet). Both France and Argentina would be big favorites over either Portugal or Uruguay. Spain and England would be heavily favored in quarters if they get there.
3) Semifinals: Spain versus Brazil is by far the most likely match-up.
4) Finals: Tight would be favored in Spain versus Brazil, but Brazil would be favored at this point.