capacity of a communication link based on QPSK modulation

does any body know how I can define the capacity of a communication link based on QPSK modulation?
does it have any thing to do with the Shannon Theorem?

QPSK is only a modulation scheme. i.e. the Eb/No in Shannons theorem becomes Es/No. i.e Eb/No= Es/No *1/R . for QPSK we transmit twoice the number of bits as BPSK i.e. M=2.

channel capacity theorem a.k.a. Shannon's Theorem.

Is Es/No is effected by the type of coding scheme and modulation being used? e.g if we have two systems with same modulation technique(qpsk) but different encoding technique( one is bch concatenated with ldpc and other is reed solomon concatenated with ldpc) does they will have diff Es/N0 at Eb/No=-2.54db and coding rate =1/4? or Eb/No= Es/No *1/R will be used for both of them ?explain the answer also .

Thankyou