Can spermatoza be identified under microscope if there dead and if so for up to how long?

Yes sperm can be seen under a microscope. It's actually quite fun to see. Sometimes it can appear in a urine sample. When you look in the microscope you may see moving and non-moving sperm. If its moving those sperm are still alive and vital while the ones floating are considered dead. Eventually after a couple of hours all the sperm will stop moving. They can be visible for hours as long as the slide doesn't dry up.