Yes, if it was a payment for 2018, then it should be included in your 2018 estimated tax payments. The 4th quarter payment due date is January 15 of the following year.
If the January payment is a state tax estimated payment and you are itemizing your deductions on your federal return, the January payment will not be included as an itemized amount as only tax payments made in 2018 qualify, but the payment still will be included in determining the amount of taxes paid for 2018, plus whether you owe any additional or are due a refund on your state return.
