A draw is very unlikely to happen at the moment. There are two days remaining and South Africa are following on and at the moment are 333 runs behind. In two days they will either need to knock them off and them build a small lead, one that is bigger than what England will have time to score.
They will be looking for a couple of big tons, and I have that feeling about Amla, I think he will score big (150+). The South Africans might need to bat for two days, and after their first innings it doesn't look likely.
There are four overs gone, and South Africa are 13/0. England will come back tomorrow rejunivated and refreshed and with a new ball in hand, looking for early wickets. The first hour of play might go a long way towards deciding the out come of this match, and if South Africa can survive it, they will be in a strong postion. However, if England can pick up one or two wickets, South Africa will have a very tough situation on their hands (well I suppose they already do to be honest).