Yes, Bernie Sanders can secure the senior citizen vote. His position on social security and medicare are in favor of the needs of the elderly population. As people grow into old age, they have growing medical concerns that require check-ups and treatments that are often too expensive for the average citizen without medical insurance.
Bernie Sanders is the oldest presidential candidate and he has more thunder than his younger opponents. He already has Dick Van Dyke in his corner and as long as he doesn't alienate his fellow old people he should be good. Sanders has a lot of promise and I think old people would really respond to him.
I think it may be difficult for Bernie Sanders to secure the votes of older generations. His campaign has been able to attract the attention and support of the younger voting demographic. I feel that Hilary Clinton is much more popular and more appealing to the older generation of American voters.
First, please define 'old people'. Second, the elderly don't necessarily vote as a bloc. I sincerely doubt there is a meeting at the retirement home in which all the seniors agree to cast the opinion in a particular direction. I doubt in that meeting they can all agree on which flavor juice they want to drink. The older we get, the more entrenched our beliefs become, left or right. A candidate that actually looks his age is unlikely to change that.