Interfaces between magnetic topological insulators and metal layers can significantly modify electronic properties and enable the design of novel quantum states. Using density functional theory (DFT), we examined the electronic structures of MnBi2Te4 with Au adlayers across various configurations. Our results show that the surface states are highly sensitive to the interface geometry, Au concentration, and distance from the surface. The energy position and spatial proximity of Au bands determine whether the topological surface states (TSS) are preserved or disrupted. Depending on the configuration, we observe either a notable enhancement of the TSS energy gap – up to three times that of pristine MnBi2Te4 – or the appearance of Rashba-like states with strong out-of-plane spin polarization near the Fermi level. These findings highlight the potential of interface engineering for tuning topological and spintronic properties, providing a foundation for stabilizing quantum Hall phases and enabling next-generation quantum devices.