Can the Commissioner of SGST revise any order passed under the Act by his subordinates?

Yes. Section 80(1) of SGST Act authorises
Commissioner to call for and examine any order passed by
his subordinates and in case he considers the order of the
lower authority to be erroneous in so far as it is prejudicial
to revenue, he can revise the order after giving opportunity
of being heard to the noticee.