Calculating Fc (cutoff) of series to RC to ground on inverting input of non-inverting amplifier
The cutoff frequency is the frequency at which the gain has fallen by -3dB over the gain at high frequencies. 

(for the purposes of the below discussion, we'll ignore the high pass network R and C since the effects of R1/C1 are being examined)

If the signal was applied to C1 (rather than C1 being grounded) R2 would not matter at all- gain would be -R2/R1 for high frequencies. When the reactance of the C1 equals the resistance of R1 in magnitude you have a reduction in voltage of 1/sqrt(2) which is -3dB. R2 will determine the gain, but not the cutoff frequency. 

However it's a bit more complex in this case, because the op-amp is being fed from the non-inverting input, and the gain is actually 1 + R2/R1 at high frequencies, so the frequency at which the gain is reduced by 1/sqrt(2) will actually depend on R2. 

In an extreme case, if you short R2, it becomes a voltage follower and then Fc is limited only by the amplifier!