Waaaay too broad of a question.
You have to remember that war is simply the use of force to achieve political objectives. So to win a war, you have to consider the political objectives of both sides.
Also, air power is very rarely used in a vacuum. Air power can be used for strategic objectives (infrastructure) or tactical objectives (tanks, troops, etc). How air power is used to achieve those objectives, and how relevant those objectives are to the overall situation will determine how effective air power is overall in the conflict.
For instance, it can be argued that for the Pacific part of WWII and for Desert Storm, air power was an essential part of the strategy that achieved the overall political objective in a relatively timely manner. However, Vietnam and Korea were examples of air power being less decisive, partially because the political objectives were significantly different.
In my opinion, the only way air power by itself could decisively win a war is if your objective is utter destruction...genocidally wiping a specific piece of territory clean of anyone who lives there through the use of air-deliverable weapons. Any other objective, then it becomes a matter of 'it depends'.
FC