It will hurt the GDP by some but not a lot.
WE’re taking people who work for the gov’t off the payroll. These people produce nothing, and if anything add to the inefficiency and debt.
I would wager, that the shut will have no appreciable affect on GDP. Unemployment, maybe? Job numbers. Probably.
But so what. In fact, the silver lining might be that there will be a wholesale layoff of people in the federal gov’t and that might be a good thing.