In the short term, yes, Donald Trump stands to gain from his tax cuts. The only major cuts have come for those who fall into the top bracket - the wealthiest of the wealthy. In the long term, we have no idea. There’s more tax cutting to come, so it could all balance out and he’ll be paying the same kind of ratio as those in the bottom bracket, but it could end up so that the wealthy cuts are the only ones that get passed. There are elections coming up in less than a month, as of writing this answer, and if the Republicans lose their majority seating, we don’t know what’ll happen when the Democrats come in.
Donald Trump could stand to benefit in the long run, but he could stand to lose too.
One of the things that a lot of experts are saying is that the tax reform is going to look like it is made for the poor and the middle class. Yet, they say that in the long run, this may work well for people who are already rich. Someone like Trump who is already filthy rich can benefit the most out of the tax reform that he is creating.
It will not be evident right now and there is a possibility that it will not push through in the future but as of now, the rich people are meant to get richer in a few years because of the changes that Trump has done.