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During start phase of a jet engine, igniters in the combustion chamber create sparks to initiate combustion. As far I know, when the engine reaches self sustaining speed, igniters get turned off (this might be different (takes longer) in an Airliner due to FAA regulations during take off).
My question is how do flames in the combustion chamber (or canisters) get sustained (like a candle) without igniters support?
How does a candles flame sustain itself after you have lit it? It stays lit by continually burning fuel. The jet engine works the same way. Once the fire is lit (by the ignitors) it is constantly burning. Air is constantly being supplied by the compressor and fuel is constantly being supplied by pumps.
This is fundamentally different to a traditional combustion engine you might be trying to reconcile this idea against. In a 4-stroke internal combustion engine, for example, you have intake, compression, power and exhaust happening separately and you need spark plugs (or glow plugs) to ignite the fuel each cycle. In a jet engine, however, instead of 4 independent cycles you have a constant flow of air through the engine. Air comes in the front, is compressed by the N2 stage and fed continually into the hot section where the fire is constantly burning and then exhausts through the back of the engine.
Look at it like a propane barbecue grill or a gas stovetop -- you only need the ignitor to start the fire. Once the fire is burning it stays that way until you turn off the flow of gas.
Another answer to add to caseys:
Some combustors have small notches in their wall which create local turbulence and help to keep some of the burning fuel-air-mixture back, which helps to start ignition in the following flow. These are called flame holders.
If all of the burning gas is washed out from the combustion chamber without igniting the following gas, the ignition process will stop. This is called a flame-out. The heat from the walls of the combustion chamber will not be enough to re-ignite the fuel-air mixture, because they are cooled by the airflow from the compressor and will rapidly cool down once the flame is blown out.
Note that this effect is used to extinguish burning oil or gas wells with dynamite.
To add to casey's post, the flame holder keeps the flame from getting blown out. Its a part of the combustion chamber that allows the high pressure air from the final compression stage to swirl at a low speed to keep the flame front contained.
