Is it possible to make an eyelet hole in a canopy made from polyester fabric?

Yes, but you would want to reinforce the polyester before making the hole so that the cut threads do not unravel. Since the project is a canopy, the "eyelet" would actually be a grommet. Essentially, a grommet is the larger cousin to the eyelet. They have similar appearances, but their functions are different. An eyelet is smaller, comes in a variety of decorative colors, and has little strength. Eyelets are used for ribbons, light cords, laces, or decoration. Grommets are used for structural reinforcement to protect the fabric from tearing when exposed to stress. Grommets are used on tarps, shower curtains, canvas bags, canopies, tents, boat covers, etc.