Late to the party but, yes, the Japanese government did think it could win WWII. Why else did it start the Pacific War?
But this is, as others have pointed out, dependent upon the definition of "win."
If by "win" that means completely defeat the might of the US and British fleets and armies? No, for all but the most rabid of Japanese militarists such a feat was not anticipated.
If however, "win" is defined as the Empire of Japan emerging from the conflict in a better strategic position than when the war started, then, yes, they did think they could win.
The strategy of grabbing all those atolls and digging in to them was part and parcel of that. The islands gained were usually but barely above sea level at high tide and thus essentially worthless in terms of territory or assets gained. Even strategic position was questionable on many of them. However, the Japanese hoped that by occupying them they would force the US to pry them out of each and every one of them. And the Japanese planned on making that as bloody a thing as possible for the Americans. They gambled that as the costs continued to escalate and the gains all too minor for those costs, that the US and the UK would become ever more tractable to a negotiated peace with the Empire.
A peace in which the Empire was recognized as the dominant force in Asia and got to keep its control and access to the strategic materials - i.e. oil - it had gained through conquest. All those islands the Japanese had fought so bitterly to retain? Well, they were always but bargaining chips to be spent at the peace table achieving the greater glory of the Empire.
The factions controlling Japan also reasoned that going to war to achieve those aims was a far better thing for them, politically, than in letting the economy contract as it would if they met America's demands. Such a contraction would violate the pact they had made with the Japanese people in which they promised nothing but "good times" economically in exchange for absolute power over them. This, just like the Nazis both promised and were cornered by in Germany. An economy that, by its very nature, requires constant increases in funding just to stay even is one which, inevitably, turns to conquest as spending without growth will always destroy that economy. Hence both Germany and Japan's need for more, more, more conquests.
The Japanese, like their German counterparts, well understood that time was against them. The economies of their major opponents were all vastly larger than theirs and those opponents were rearming at rates neither Germany nor Japan could hope to match. The longer they waited to go to war against the US and UK and Soviet Union, the worse position they'd be in when the war started. So, September 1st was the kickoff in '39 for Germany and December 7th in '41 was for Japan.
We can say, in hindsight, that their efforts were obviously doomed from their outset. That, I think, severely underestimates real world effects and how close - but for want of that nail - things actually were.