One would need 3498.9 grams of O2 for this particular combustion.
The combustion reaction can be written as follows
C9H20+14O2→9CO2+10H2O
we can see that 1 mole of nonane needs 14 moles of O2 for the combustion reaction; from mC9H20 = 1 kg, one can solve for the number of moles of nonane
nC9H20=1000g128gmol=7.81 moles
(using 1kg = 1000grams and knowing the molar mass of nonane to be 128gmol );
Therefore, the number of O2 moles will be
nO2=14⋅7.81=109.34 moles
The mass of O2 yields
mO2=109.34⋅32=3498.9 grams
IF you need the quantity of AIR, just remember that air contains 20.95%O2 , 78.09%N, and a little under 1% other gasses (Ar,CO2,and others).