There is one thing you have missed – ECM will not jam bubbles. That sabre will continue to drop bubbles right on top of you, even if he is jammed.
The counter to that is to use a MJD to jump out of the bubbles, it has a long cool down. You then warp to the next gate.
Except that a good sabre pilot will burn out of his bubble and watch where you warp. He follows, and since he is faster than you he drops a bubble and you land right in the centre. He then jumps to the other side of the gate and bubbles again. Now your MJD is still on cool down, so your only options are to burn out of a bubble while a hostile fleet is heading towards you, or jump into a bubble camped gate with a sabre and other possible unknowns.
The last option is probably your best option – hopefully the sabre is alone and you can kill him and get out of his bubble before his friends arrive. If he’s not alone, or his friends arrive in time, you’re either dead or the above story repeats itself.
In other words, your options are to:
a) not jump into the gate camp in the first place… use scouts, avoid commonly camped gates
b) die… nothing wrong with that, it’s happened to all of us!
c) have enough friends nearby that you can break the gate camp. This is where the ECM option might shine, as it’ll be able to delay the camp long enough that your backup can arrive.