You can work it out.
Find the maximum current draw of the servos.
Multiply it by the number of servos.
This is the maximum all servos will draw if they all start up at the same time or are at peek load at the same time, which basically means it's enough power for any circumstance.
Your regulators will need to be rated higher than the maximum demand. So, for instance if each servo had a maximum demand of 2A, that would be 14A. So you would need a 14A regulator for these servos or put 3 x 5A in parallel, or use one 5A for every 3 servos (one will have 1 servo on, or do a 3, 2, 2 configuration).
You will also need to check the batteries can give out the required current. A 5Ah LiPo battery with a 20c rating will give out 100Amps (20x5) but a 9Ah battery with a 1C rating (if they exist) wouldn't be able to supply the necessary current and the servos would fail regardless of the regulators.
Don't forget to allow for the DC motor's current draw too.