Answer
Gauge symmetry is pivotal in the AdS/CFT correspondence, a theoretical framework relating a specific class of gravitational theories in Anti-de Sitter (AdS) spacetime to their corresponding conformal field theories (CFTs) existing on the AdS boundary. This symmetry ensures that the physical properties and behavior of the AdS spacetime are directly mirrored by the properties of the CFT, establishing a deep connection between these seemingly distinct theories.