Is the gas still good if water gets into the gas can with the gas?

Since gasoline is oil-based, gasoline and water will not mix. Furthermore, since water is heavier than gas, the water will collect in the bottom of the gas can. The gas in the gas can should still be usable. However, you should be very careful not to pour the water into your gas tank.

Personally, i would not use that gas in my car. I would use it in my lawn mower or some other gas-powered appliance. I would also transfer the gas first into a glass container so that i could observe the water in the bottom & ensure that it does not find its way into that lawn mower. The water will be plainly visible as a layer (or just a bubble, depending on how much water there is) in the bottom.

NOTE: gasoline should never be stored in a glass container, only in properly marked gas cans.