How much water is produced in jet exhaust?
According to Wikipedia Kerosene consists of molecules containing 10..16 C-atoms.
Assuming that the molecules are mainly Alkanes with formula $C_nH_{2n+2}$:

$C_{10}H_{22}$: 10 * 12g + 22g = 142g Alkane contains 22g H which burns to 22g + 11 * 16g = 198g $H_2O$ 
Ratio Water/Kerosene = 198/142 = ca. 1.39 

$C_{16}H_{34}$: 16 * 12g + 34g = 226g Alkane contains 34g H which burns to 34g + 17 * 16g = 306g $H_2O$ 
Ratio Water/Kerosene = 306/226 = ca. 1.35 

I.e. you get something between 1.35g and 1.39g Water per 1g Kerosene.

Comparison to Gasoline:
Main difference of Gasoline is that molecule chains are shorter (4-12 C-atoms).
I.e. H/C-ratio will be higher, i.e. Gasoline will yield more water per fuel than Kerosene.