What is the maximum number of electrons in each orbital?
The maximum number of electrons in any orbital is two, regardless of the nature of the orbital. This is because every electron in an atom must be unique - different in some respect from any of the others.
The differences can only come in the way of the four quantum numbers required to specify an electron:
The principle quantum number,
The azimuthal quantum number,
The magnetic quantum number,
By this point, the orbital in question has been uniquely characterized.
This leaves the spin quantum number,
Thus, each orbital holds up to two electrons at most.