It is possible to kill someone by striking the throat. It is possible to cause significant damage to the vocal chords, severe structural damage or swelling that causes the throat to constrict-leading to death.
Due to variations in anatomical strengths, disease process, etc. between individuals it is difficult to tell how much force is needed to cause significant damage or death. It also depends where you strike.

To sum up-if you want to reduce the risk of death or serious injury,do not strike the throat.