Graves disease can it be deadly?

Rarely It can be: Often graves' disease is not fatal, but it can be so because it has the potential to cause cardiac arrythmias (irregular heart beat) such as atrial fibrillation causing blood clot which can then cause strokes etc, if treated appropriately, you should be ok. Follow doc regularly because u may end up going hypothyroid eventually which also requires treatment. Good luck.

No, but: Treatment is needed to prevent your thyroid from getting too overactive, good medical care will keep you on a healthy track.