To make use of them would require ADCs and Linux driver experience. I don't know if any drivers exist that could make use of 8 channels today, so you may need to research that or develop/modify existing drivers.
You could use stereo per channel (to allow making use of typical audio ADCs and have less to modify for existing drivers), or in fact any number of streams
(hundreds are supported) in a TDM format (e.g. lots of A- or u-law) which is a bit more specialist. Basically it is _extremely_ flexible - one of the best boards for audio applications.
EDIT: sorry, looks like I can't link to the image directly. You can see it here BBB - Building a DAC search for the text 'AXR' and there is a diagram there - the one with blue and green shaded blocks.
