The coupling capacitors at the inputs/outputs should be 220nF for GMSL using the normal reverse channel and 47nF for parts using High Immunity Mode, ideally with the REV_FAST bit set to '1' which increases the reverse channel rate back to 1Mbps from 500kbps set in HIM. The reason for the capacitor change is that HIM adjusts the amplitudes and filter frequencies allowing use of smaller capacitors which makes the parts less susceptible to low frequency noise injected on the coax since this capacitor and the 50 ohm input termination forms a high pass filter.
The voltage rating on the capacitors is dictated by automotive system requirements. Automotive systems typically have a 50VDC requirement. Select a capacitor voltage rating that will allow for derating over all operational conditions. Include sufficient margin to allow for design tolerances. Capacitor size 0603 and larger with 50V or greater voltage rating are generally acceptable. Catacitor size 0402 is generally not acceptable in automotive systems.