A survey showed 62 percent of those polled by peil.nl expect the Netherlands to win after their 3-0 defeat of Latvia on Wednesday helped secure a place in the last eight.
Dutch politicians are among those to have expressed support for Advocaat, slammed after a 3-2 defeat by the Czech Republic followed his controversial substitution of winger Arjen Robben.
Ministers criticised a call by a television commentator after that game for Advocaat to be stoned
"Such abuse goes absolutely too far," Interior Minister Johan Remkes was quoted as saying in the Algemeen Dagblad.
A new website offers fans T-shirts to show their real feelings for the coach: "Our Dick has balls", "Our Dick never gives up", "Our Dick will always score", "Our Dick is 1.69 m tall" are some of the slogans to choose from.
Dutch supporters have deluged the Czech embassy with messages of thanks and flowers after the Czechs' 2-1 defeat of Germany ensured the Dutch a quarter-final place.
A website set up to thank the Czech "saviours of Orange" has registered almost 75,000 Dutch thank-you.
