Any idea what I am doing wrongly?
If you use a M5Stack Fire, maybe you have enabled the PSRAM in the compile options of the arduino IDE (Tools ==> PSRAM)?
As written here, this does not work with the GPS module:
I have a M5Stack Fire & GPS Module (see also here: http://forum.m5stack.com/topic/1131/base-m5go-bottom-issues-with-uart-port-c) and your sketch works for me (= I see the GPS raw data).
What does that HardwareSerial GPSRaw(2); mean?
Google directly delivers information for this topic. Try to dig into it yourself, it seems you have some basic knowledge in coding. If you are still in trouble after some hours, come back to us :)