The heat of combustion of 1 litre of petrol (gasoline for US readers) is 32MJ and this is equivalent in terms of heat produced to 700g of gas.
If you normally allow 40g gas per day, and assuming similar stove efficiency, this is equivalent to 57ml petrol so 1 litre should last 17 days.
However you need to prime this stove. You could use petrol but that will reduce the number of days that 1 litre will last, or esbit tablets. Also bear in mind that the stove efficiency is reduced if you turn the flame up to 'full blast'.