My primary area of practice is cross-border tax. I deal a lot with the United States. One of the major advantages of the Canadian taxation system is that we have tax integration in Canada, meaning that if you earn a dollar personally versus earning a dollar in a corporation, and are ultimately paying that out to a shareholder, you pay about the same amount of tax. It doesn't matter which entity it's earned in.
At the end of the day, a corporate tax cut results in less tax overall for the individuals who are earning income from the corporations, be they individuals or corporations. So it's a bit of a misnomer to say that a corporate tax cut does not benefit individuals, because it does. The ultimate flow-through of that income is tax left to individuals.
The other key tenet is that “corporation” doesn't just mean big business. There are a lot of small businesses that drive the economy. As well, the corporate tax cuts flow down to the small businesses, and this helps the economy as a whole.