Meaning of "Fifty years ago, and his father had been dead for thirty years"

Question

In the story Christmas Day in the Morning by Pearl S. Buck there is this sentence

He woke suddenly and completely. It was four o'clock, the hour at which his father had always called him to get up and help with the milking. Strange how the habits of his youth clung to him still! Fifty years ago, and his father had been dead for thirty years, and yet he waked at four o'clock in the morning. He had trained himself to turn over and go to sleep, but this morning it was Christmas, he did not try to sleep

What does it mean exactly?

Answer 1

He's reflecting on a memory from 50 years ago (it might not be exactly 50 with poetic license). And, at the time of the story, his father has been dead for thirty years. The specific memory he's recalling is mentioned in the following text:

Why did he feel so awake tonight? He slipped back in time, as he did so easily nowadays. He was fifteen years old and still on his father's farm. He loved his father. He had not known it until one day a few days before Christmas, when he had overheard what his father was saying to his mother.

So, if the story was taking place in 2020, he's remembering an experience in 1970, when he was fifteen, and his father died in 1990.