"and that should be the crux of the argument. Will it actually generate more revenue?"
When Reagan cut taxes in the 1980s it doubled the federal income tax revenues. It also had the unintended effect of "progressivizing" the tax structure by shifting it to the right. In other words, cutting taxes noy only helps the rich (it does), but it helps everyone else as well.
Consider what would have happened if instead of cutting taxes on the wealthy, Reagan had increased them. First it would have reduced the incentive to efficiently utilize labor or captial. Instead, people would have elected to spend their surplus wealth, as opposed to investing, or spend more time on leisure activity than working. And remember, these are the country's highest income earners, providing the most valuable services to the greatest number of people. So in addition to decreased tax revs, you are also suffering an increasing scarcity in already scarce labor markets. Do you really want to discourage doctors from working more? I certainly don't. It' sure not going to do anything for healthcare costs.
Wealth creation is a synergistic process that requires both labor and capital, and the process will work most effectively when those factors of production are able to benefit from it. IMHO, income should be treated like equally, regardless of where it came.
As we often see here, the wealthy in this country are regarded with a lot of derision, especially by those on the left. I can only guess that it is the last vestiges of marxism, under which the rich only get rich at the expense of the poor. The obvious problem with that theory is that if you were to eliminate the rich altogether, it wouldn't make the poor any better off. It's not going to make them more entrepreneurial, or more productive, or more qualified for a high paying job. In all likelyhood the poor would be far worse off, as many are currently reliant on the rich to sustain them. Imagine what would happen to a four year old who all of the sudden found herself alone without parents to care for her. Would she be able to produce her own food or see to her own medical needs? Most likely not. That would be the vast majority of the poor in the absence of the rich.