Is there anyway that you can put a table/array into a gem window?
Or is there any other way to project a adc input into a gem window?

@H. Take a look at [pix_data] especially the example pd/extra/gem/examples/10,PixDataSimple.pd
You should be able to plot spheres, squares etc. using your data instead of the [random] generators in that patch. You will also be able to colour data with an "overlay" jpeg image as in that patch.
Otherwise you might find exactly what you want here....... https://forum.pdpatchrepo.info/topic/7958/display-waveform-in-gem
Like this.zip
David.