I basically have a requirement where I have to find the number of data packets from the interface machine to the PI Data Archive per unit time. Is there a way to do this?
Using PI based tools? Not really. Would suggest you try a packet sniffing tool such as Wireshark, filtered to outbound traffic on TCP port 5450.
As John said, you get the most control with a 3rd party tool like Wireshark. Otherwise, not sure if this will meet your needs, but the PI Data Archive has some very basic counters in the Network Manager Statistics:
Retrieving data ...