Trump has everything to gain from cutting the inheritance tax.
Usually the estate goes goes to the spouse, with no tax but if his will moves his money to the children, they are responsible for paying taxes.
So, the typical tax at that level is around 40%. If he eliminates that, The trump kids get a huge tax break worth million or billions. Hard to say really.
From what I can gather, eliminating that type of tax only serves the very rich. There is little tax on the lower end of the scale..
From my point of view he's trying to remove the inheritance tax for his family's gain. Looking at current US code the IRS limits are at 5 million dollars tax free the Trump has more money than that. So eliminating the estate tax does nothing really for most people. Its self serving.