They are not always directly related and can depend on the type of modulation being used. Pulsed lasers can have a PRR but they are not transmitting any data so they would have 0 Gbps bit rate. PPR is the number of pulses per second being transmitted and the data rate is the amount of data being sent per second. A 10 gbps would have a data rate of 10 gigabits per second, but without knowing the modulation format you cannot say anything about the PRR.
If the modulation format was say phase shift keying then you could say the PRR is 10GHz, since each pulse corresponds to one bit of data.