Yes, estimated taxes paid in January 2018 by the January due date count as 2017 tax payments.
But also note, if you itemize deductions, the STATE taxes paid in January 2018 will not be included in the 2017 taxes paid amount line on Schedule A. But they do count on your state return as 2017 taxes paid, and can count as state taxes paid if you itemize on your 2018 federal return.
