Tomorrow will be a rare day when the whole of Pakistan will be hoping for an Indian win against South Africa.
On all other days, Pakistan would never want India to win matches and the same goes for the Indians. This was witnessed the whole of India was in joy when Pakistan lost to Zimbabwe.
So the formula is, India wins against South Africa and Pakistan wins against South Africa and South Africa will end up with 5 points while Pakistan ends up with 6 points provided they win all three matches.
More details equations of all teams in Group B can be found here T20 World Cup scenarios: Pakistan rooting for India to stay alive