It is possible but EL wire work with 100V at a few hundreds hertz. So need to add some interface circuit to drive EL wire with the Espruino.
The how many answer depends on the possibilities of the interface circuit. I have seen an EL shield at seeedstudio for Arduino which was able to drive four EL wires. Each of them could be powered on/off.
They also have another one that maybe more interesting working both on 3V and 5V but driving only one EL wire
You can also just switch power to a standard (cheap) supply/inverter for the el wire with a mosfet. Note that you can't pwm it, the inverter will not like that. I do that for backlighting for the display on my desk lamp (with el panel).
You will need a separate supply for all but the tiniest el wire projects
If you want to dim the EL wire you shall change the frequency of the inverter
Iv seen tutorials online with el wire and a shield for adruinos. Is it possible to connect el wire to arduino if so how much could i power or how many?