This purple kush plant is in its 7th week of flowering and it’s supposed to be done flowering in 8 weeks . The hairs in the buds are still white and haven’t turned red / amber . Any suggestions ? How many more weeks of flowering do you think will be required ?

I'm thinking you still have another 3-4 weeks left to go.
Have you tried looking at the trichomes with a jewlers loupe or some sort of magnifier? Just based off of your pictures I would say a few more weeks at least.