how to create GIG without any video
Seriously? Just create a new gig, and don’t upload a video.
Certain categories require Video to be uploaded and that is mandatory. If you want to create gig in that category then Uploading a video is must otherwise a Thumbnail photo will work.
No need video but video is needed for ranking.
As far as I am aware, having a video on your gig does not guarantee a better ranking in the search results.