How to Calculate the Impedance of the Capacitor T network?
I'm afraid to say that the circuit is a bit useless. At first glance it appears to be a 2nd order high pass sallen-key op-amp filter but, on closer inspection of components around the Vin- pin of the rather-boxy-looking op-amp, it appears the circuit has been drawn incorrectly and quite possibly made incorrectly. R5 should provide feedback from the op-amp output to the junction of C2 and C3 but unfortunately it's not connected to the output but to Vin- rendering it ineffectual.

What you appear to have is somebody's interpretation of what they should really have and, I expect that R6 has been pushed ever higher in value to obtain some partially useful filtering that the designer believes is correct.

Where did this circuit come from?