Determine the orientation of an ESD protection chip
Yes. Pin 2 connects to the anodes of the diodes,  



so you should measure a 1 V drop maximum(*) from pin 2 to any of the other pins. If you have the device reversed and would test this from pin 5 instead you'll need to overcome the diode's breakdown voltage of minimum 6.1 V first. So if you apply 3 V (with a series resistor) you'll have current from pin 2 to any other, but not from any of the other pins.  

(*) Forward and breakdown voltage are listed in table 2 on page 2 of the datasheet.