First off, if you read the tax plan, it's not "tax breaks for the rich", it's tax breaks for everybody. Secondly, we don't "give billions to huge companies", it's THEIR money to begin with, the government lets them keep more of it. Thirdly, we have the highest corporate tax rate than any other developed nation.
Now, will this tax plan stimulate the economy? It might, the thing is an economy is affected by hundreds of variables, you can't make a causal connection to ONE event and the whatever the outcome is. It will HELP the economy, but that doesn't mean the economy will go up necessarily, it could mean whatever damage was inflicted by another event, was mitigated.