How can you possibly expect an accurate answer when nobody knows the governing specification, the base metal, or intended service of service of the weldment?
Aanish,
What code of construction are you welding to? If you have a qualified welding procedure, then to what code was it qualified? It helps if you have that information along with client requirement. (if any) Some client specifications are specific about weld repairs. But in general, if you have a GTAW/SMAW qualified welding procedure to ASME Sec. IX, then yes you would be able to repair the weld using either of those welding processes.