Will Anyone Die With Myasthenia Gravis?

I have a niece she is around 35-37 years old and was diagnosed with mg in 2005. Can she die from this and if so and if so how many years will she live???? She can still walk and do normal activities but she is not in remission. She takes medication and go to her treatment. She complains of pain and doesn t always take her meds.I try to explain to her she needs to take her meds but she dont like the way they make her feel. Please help me so I can explain the how serious this is.