The Child Tax Credit is worth $1,000 but that does not mean you get a refund of $1,000. The Child Tax Credit reduces your taxes. It is not a refundable credit like the Earned Income Credit (EIC).
If your taxes are $507, TurboTax uses part of the $1,000 Child Tax Credit, to pay the $507 so you get what is left, the $493. For additional information, see What is the Child Tax Credit?
Note: If you have other credits, TurboTax will take a portion of each of those credits and split them among the tax owed.
You may qualify for the Additional Child Tax Credit. If you do, TurboTax will calculate it. See What is the Additional Child Tax Credit?
If your income is too high, the Child Tax Credit is also reduced.