、。
There's not a soul yet in front of the main gate.
Literal
Front-gate front [at-には], still person [gen-の] figure [even-も] doesn't-exist.
人の姿も is a literary way to say 'not even the shape of a person' — using 姿 ('figure, form, shape') to emphasize absence. も after the subject marker forces 'not even,' stronger than a plain negative. には stacks location に with topic は, scoping the scene. 正門 ('main gate') is the standard word for the front gate of a school, company, or institution. A compact piece of scene-setting prose.