Joseph C. Wilson's trip did not affect George W. Bush's decision to invade Iraq. It was clear that Joseph C. Wilson was totally against the invasion of Iraq but Bush decided to move forward anyway. Clearly to hush him up, Joseph C. Wilson's wife was outed as a cia agent.
I think the biggest reason why George Bush invaded Iraq was either to finish the mission that his father started several years earlier or to get oil from the Iraq land. Either way, Joseph Wilson did not have much influence over whether we went in or not. Brush wanted to go in anyway.
Joseph C. Wilson's trip likely did not affect George W. Bush's decision to invade Iraq. Plenty of other factors pushed Bush in the direction of invading the country. With that in mind, Wilson's trip was for different reasons and didn't have much of an impact upon politics at the time.
No, Joseph C. Wilson's trip did not affect George W. Bush's decision to invade Iraq, because he acted according to what he thought was best for the country. Wilson only took the trip to make a political statement. He was an adversary of Bush and he wanted to undermine Bush's authority. Wilson wanted to make a point, not the other way around.
People love to point fingers at certain reasons for people doing large scale acts - especially unpopular or secret ones. After the Valerie Plame incident, people have more awareness of Wilson, but the truth is that Bush and Congress made the choice based on a combination of heightened feelings about the reason and mis-analyzed information.