Is it possible to connect eight digital inputs to a digital output?
it depends on the digital inputs. If each individual digital channel is the same digital protocol (frames). Then you can apply a process called "Muxing". This we take your 8 paralleled lines of data, then apply it to a device called a parallel to serial shift register (74HC589 for example)  then you frame it out back to you eight data lines. These of IC's are based off the device known as a flip-flop. See: http://www.electronics-tutorials.ws/sequential/seq_5.html as they go into great detail in construction and operation.