It would be excluding refer section 51 of CGSt ACT.
Explanation.––For the purpose of deduction of tax specified above, the value of supply shall be taken as the amount excluding the central tax, State tax, Union Territory tax, integrated tax and cess indicated in the invoice.
Moreover, in service tax era, TDS was deducted excluding service tax, hence same will continue in GST era.
CBDT has come up with Clarification circular on this matter vide Circular No. 23/2017 dated 19th July 2017. TDS will not applicable on GST portion of Service if GST portion separately indicated on the invoice.