Business rather than in software, and aparatoj part, because usually, when you connect multiple monitors to a PC is a separate desktops and applications deployed to the same table.
Then, you can merge all monitors into a single table, and withdraw any applications on all monitors at once. This is done via NVIDIA Surround (only for three equal resolution monitors) or using AMD Eyefinity (without limitation). Of course, the video card should support one of these technologies.
AMD Eyefinity and I think this is what you need, although personally I'm not a fan of AMD, but with AMD Eyefinity worked and was very pleased.
In AMD Eyefinity mode normal apps will work, but performance is unlikely you will please. Except that a few little videos in SLI to run, and hope that the application is friends with SLI as it should.
Further, the content.
Video 8K find unlikely, exotic. Except to order shooting somewhere. But look at the drains, video banks, suddenly there is something.
I would suggest to hire a developer/Studio, and write your app optimized for 8K. Type animated demo in 3D. The emphasis on high quality textures, nice animations and effects to create fake volumetric light and caustics. And a minimum of heavy shaders. With a good artist this can be done very nicely.
PS: still, as an option, you can run the application in windowed mode, stretch to all monitors window (if the app allows) and then switch the window mode to "borderless". But it's a pain, don't know what the finished software can I hack Borderless Gaming to do. And in any case, the performance of the application in this mode drops by an order (i.e., fps may upasi ten times).