A gas smell is almost never normal.
There are all sorts of interlocks in a boiler that could prevent it from firing: low pressure, low water, thermocouple (not sensing the pilot is lit), defective gas valve, over temperature (this may have occured and tripped a safety device requiring a manual reset); plus, probably others.
So, you'll need to dig out the service info and trace things to see if all of the interlocks are closed to allow it to fire. It could be a defective switch, or a real safety issue.
If you really do smell gas near the applicance, I'd call for help and maybe get out of the house while doing it - things can go boom. All it takes is the right fuel/air ratio and a spark to literally level a house.