Cavity-filling is a common phenomenon whereby a fluid fills all or part of a cavity, displacing another immiscible fluid. In this study, we experimentally and theoretically investigate the effects of the cavity aspect ratio, channel width, tilting angle of the cavity leading wall, and inlet flow rate on the morphology of the water-air interface and the filling fraction of various cavities. Considering the influencing factors, we derive two formulas for predicting the filling fraction, and verify these expressions against experimental results. The findings of this study provide theoretical guidance for applications related to pressure-driven filling of cavity structures.