"Much discussion has occurred regarding the optimum
capital gains tax rate, with some calling for reductions in the belief that a lower rate will provide investors an incentive to invest in new stocks—which supply siders claim encourages the creation of new jobs, reduces unemployment, and has the paradoxical effect of increasing tax revenue."
https://en.wikipedia.org/wiki/Tax_cut
"
Tax Cuts
During recessions, the government will occasionally offer a
tax cut as an economic stimulus. In rough terms, a tax cut of one trillion dollars over ten years will "give back" an amount equal to about one percent of consumer spending annually over that period."
http://www.moneychimp.com/articles/econ/tax_cuts.htm
Just the first 2 link when I searched tax cut. Tax cut is not new. Why don't you just go research how previous tax cuts affected the economy. But also check out government spending and other stuffs. But in general, tax cuts have been beneficial. Also, it was the Democrats who originally favored tax cuts.