Is it still tracking ahead of PS2?
If we strictly take the first 13 fiscal quarters for both consoles, yes. The PS2 had shipped 51.2m by March 2003. The PS4 has shipped at least 55m by December 2016.
The catch is that the PS2's first three quarters were Japan-only while for the PS4 only one quarter for Japan is missing in this 13-quarter-period. Taking 12 quarters for Japan and 13 quarters for America and Europe for the PS2 to match the PS4's launch logic, we get this:
Japan - 12.47m
America - 29.09m
Europe - 24.27m
Total - 65.83m
That puts the PS2 10m units ahead of the PS4. Numbers taken from the Wikipedia page which hosts data extracted from Sony's financial reports.