Do I need to declare tax on bitcoin earnings as a non-resident?

I am a Temporary resident in South Africa using a work permit. I have a permanent Job and pay income tax from my salary. I however started trading different gift card codes in the US and UK online for bitcoins and have made a lot of profit in the last 8 months(well over R100k). These funds were in bitcoins which I later withdrew to my Absa account. Do I need to declare tax on these earnings as I am a non resident.

Yes you need to declare the income you earned in your ABSA account and also deduct any expended you incurred while generating this income.

Last question, does this mean I have to pay provisional tax on this income as it is not taxed before I receive it?

If you are earning more than R30 000 in profit then yes.