It depend upon you registration. If you gst registration is regular then 18% is taxable and should be collected from the customer.
If the gst registration is of composition type then 5% gst to be paid by the restaurant on their supplies but not to collect such tax from the customer.
TRUE, REFER: CIVIL APPEAL NO. 21790 OF 2017 (Arising out of S.L.P. (C) No. 28685/2015)
FEDERATION OF HOTEL AND RESTAURANT ASSOCIATIONS OF INDIA Vs UNION OF INDIA AND ORS. (SUPREME COURT)