The child tax credit (CTC) is limited to your tax liability. The CTC is a non-refundable credit and can only reduce your income tax to 0, It can not help you beyond eliminating your tax liability.
So if you have enough W-2G income to have a tax liability, you will get enough of the CTC to wipe it out, but not the rest of the $2000 (unless your tax liability is $2000 or more)
For people who have more than $2500 of earned income, some o the unused CTC is usually given back to them thru the "Additional Child tax credit"*. You won't get any ACTC since you have no earned income.
*That is, part of the CTC may be on line 18b of form 1040 (2019 version) instead of line 13a (lines 17 and 12 in 2018). The ACTC is calculated on form 8812 and is basically 15% of your earned income over $2500. The ACTC is a maximum of $1400 per child (not $2000).
