Yes, as long as he meets the other qualifications (has a social security number, for example). Be sure to indicate the he lived with you the whole year in the "My Info" section. Here is an excerpt from IRS Publication 501.
Death or birth of child.
A child who was born or died during the year is treated as having lived with you more than half the year if your home was the child's home more than half the time he or she was alive during the year. The same is true if the child lived with you more than half the year except for any required hospital stay following birth.
Additionally, he may also be qualified for the third round stimulus payment ($1400) that will be added to your tax return as a Recovery Rebate Credit. You will be asked during the federal review about any third round stimulus payments you already received. You will enter that amount and any missing amounts (added dependent, for example) will be included on your tax return automatically.
You can view your form 1040 to see line 28 for the Child Tax Credit and line 30 for the Recovery Rebate Credit.
"Tax Tools" in the left hand menu
"Tools"
"View Tax Summary" in the main screen
"Preview my 1040" in the left hand menu
Yes he does.
Make sure you have entered your child as a dependent in My Info, and that you have entered the child's Social Security number. If your child was born in 2021make sure you said he lived with you
the whole year.
There is an oddly worded question that asks if the child paid over half their own support. Say NO to that question.