Well, it depends on what you mean by support, but I'll make the assumption that you mean across and through the collector to emitter connection, which is typically used as the output. The Vishay 4N35, which I will assume is typical, will tolerate up to 50mA of DC current and up to 100mA for short durations of 1mSec or less. It will tolerate a voltage of up to 70V. It also will only tolerate a combination of current and voltage up to 0.15 Watts (current x voltage = watts).
The AC behavior depends on what shape of AC. The peak current limit would remain the same, 50mA, even though it is going up and down repeatedly and the peak voltage rating would remain the same. The total power that the device could tolerate would have to be adjusted up or down depending on the average RMS voltage multiplied by the RMS current of the AC.