My son graduated college in 2019, he's a missionary in Louisiana and we are supporting him financially. Do we still count him as a dependent?

[DanielV01]

Maybe.  If he made less than $4300 and you provided more than 50% of his support, you may still claim your son as a qualifying relative even though he did not live with you.  Otherwise, you will not be able to claim him.  The benefit is somewhat limited ($500 for the Other Dependent's Credit), but this year you would also qualify for the $1400 stimulus payment as well, which the IRS has been issuing on a "step up" basis if the amount was not submitted with the original return.