Greste's parents recently returned from an eight-week visit to Cairo. Mother Lois Greste said the last time they saw him "wasn't what you'd say was the best day, but it wasn't the worst day".
"He's fine, he's coping well, and he says that he knows that when he's had a bad day, that he'll have a good day following. So he realises that this is just a phase that he's going through," she told PM's Mark Colvin.
"There's lots of rumours that go round in the prison as well ... some of the news bites that he does manage to hear, and it can't help but build up his hopes.
"Some of the rumours have been saying, 'I hear you're going tomorrow', and of course tomorrow comes and nothing happens.
"So he's decided really that until the authorities tell him to 'pack your bags, you're out', he won't believe it."
Greste said she would only believe her son had been released when he was on a plane and out of Egypt.
Earlier this month Egypt's Court of Cassation ordered a retrial of Greste and his colleagues and at the time, his parents said they were pinning hopes for their son's freedom on his chances of being deported before a second trial.
But Mrs Greste said the family remained in the dark while they waited for things to happen in Egypt.
"There's a possibility of the retrial, there is the possibility of a decree, and also there is the pardon that was supposed to come out on the 25th of January for Revolution Day," she said.
"All of that has been put on hold because of the Saudi king's death, and they're now in mourning for this week. So at the moment we're in limbo."
She said to pass the time her son finished two assignments for his distance university course.
"This is helping him enormously. Something to do and something to feel that after all of this is over, he will have achieved something, it hasn't been a waste of time," she said.