1. Afganistan is providing good jobs to 70,000 pakistanis.
Ok, and? How many jobs does Pakistan provide to Afghans?
2. Afghanistan is contributing towards pakistan's economy.
Well technically, yes, a contribution of 0.0001% toward GDP is still a contribution. The question is that whether this contribution really matters.
3. 1 Afgani = 2 pakistani rupees.
1 INR = 2 Japanese Yen
To use exchange route as some sort of a threshold says your knowledge about economics.
4. A pakistani earns a monthly salary of Rs17,000 in Lahore but gets 70,000 Pak rupees in Afghanistan.
Sure, just 1 single Pakistani. 1 single person is irrelevant.
Out of 4 million Afghans in Pakistan, probably hundreds of thousands earn good salaries in Pakistan while earn 0 Afghani from Afghanistan.