This is where the opposing view will typically point at social programs, for starters. I suspect that no amount of feasible cuts to social programs would fully subsidize the spending that you mentioned and reduce the deficit but don't have the numbers.

To their point though, a person could reasonably support the tax cuts and seek to reduce the deficit on the premise that reduced spending would satisfy the latter over time. Whether or not the current administration is making a genuine attempt to do so is a separate argument and one that their comment did not mention.