Settling time is defined as the time it takes the output to go from 0V to within 1/2 LSB of the full-scale value with a load of 10pF. This is independent of sample rate or communication speed. The MAX5541 has a specified 1us settling time.
The MAX5541 digital SPI interface has a maximum clock rate of 10MHz. Since the maximum theoretical throughput is one bit per clock cycle, the MAX5541 can only transmit 10Mbps. At 16 bits per sample, the maximum continuous sample rate of the MAX5541 is 10Mbps/16 = 625ksps. Since the analog settling time is less than the maximum sample period, 1/625ksps = 1.6us, the output accuracy will not be limited by the update rate.