Superconductor-semiconductor coupling in hybrid nanowires plays a pivotal role in Majorana devices. Here, we demonstrate this tunable coupling in PbTe-Pb nanowires and its impact on the induced gap and zero-bias peaks (ZBPs). In the strong coupling regime, the device reveals a clean superconducting gap, where robust and non-robust ZBPs are observed in distinct magnetic field ranges. Conversely, increasing the gate voltage drives the system toward the weak coupling regime, where the gap becomes narrow and soft. Consequently, robust ZBPs disappear while non-robust ones persist. Our results establish a direct link between tunable coupling and robust ZBPs, providing guidelines on engineering Majorana zero modes and topological qubits.