A number of ways.
If cutting taxes doesn't significantly increase consumer spending, which is what many economists are predicting will happen this time, there's no bump in demand to justify more hiring. It is supply-and-demand 101 - without consumer demand, there is no reason to increase production/supply.
If enacting what is essentially an economic stimulus during a period of full employment and consistent growth prompts interest rate hikes, the benefit to many low and moderate income consumers will be erased by the higher cost of consumer debt.
If the tax cuts are offset by cuts to benefits with a high multiplier rate, like food stamps or social security which are spent almost immediately and in full by most recipients, the loss of that spending can outweigh the gains created by consumers with slightly more in their paychecks.
Tax cuts don't create upward pressure on wages, and unless they're targeted toward the specific demographics that will see the least benefit from this (low-income households, particularly those with children, cash-strapped middle class parents of teens and college students) they don't provide a sustained boost in consumer demand. Plenty of CEOs have outright said that the benefit from this cut will go into stock buybacks and higher dividends, both of which have a low multiplier effect in the bigger economy, and it does appear that there is significant support in Congress for cutting high-multiplier safety net programs to offset the cost of the bill.
