How can I stain or glaze the glass so it's not clear on patio table?

Whatever you do, I would apply to the underneath side of the table to make it more weather proof. Also makes the top of the table easy to clean.

You can stencil from under glass with acrylic paint or if you are good you can paint a picture from underside-then just seal when finished

Try mod Podge and newsprint on underside of glass

These are many paints made for glass avaliable. I agree with Naomie, do it on the underneath. I have used Krylon sea glass spray paint with beautiful results. It comes in several colors. Best wishes!

Staining comes natural at my house! (Unintentional at that!) ;D

However, to stain glass itself may be tricky. Perhaps you may want to try using window film. This way, you can change if/when you want and/or even place leaves or other decorative flat items on the table under the film.

Mac Tac is greatest I put it on end tables and redoable if it gets ruined. Can change it to decor liking very easily.

places like michaels have etching kits

I would use Unicorn SPiT, which is a primer, paint, and glaze in one. Then give it 3-5 layers of OIL based spray sealer so it will be resistant to the weather. U S is available at Michael‘s, Hobby Lobby and Walmart for sure. Please post your cleaning, painting, sealing and another photo or two on Hometalk. We must see how this turns out! ☺️

I have used a frosted spray paint that I really liked.