You HAVE a cabinet at the sofa. Too crammed in. Try that one, but more importantly? We need pictures of the entire room, nor one weeny corner.

That's how you get the best suggestions

This below ? No......try left of fire

Consider putting the television on the wall where the mirror is (but lower) so that it can be viewed at normal height.

Have mounted the tv above the fireplace in several projects and it has never presented a problem. The cabinet in the corner is crammed in there. Might suggest that you have built-in cabinetry installed and turn that entire end of the room into storage and display.

Just show the whole room, please? : )

Yes we need to see the whole space but generally storage needs in a LR are minimal so what exactly do you need to store and I agree that cabinet in the corner has to be moved . I never put a TV above a FP unless there is really no other wall for it so I agree next to the FP where the mirror is on an articulating arm with a low cabinet under it would solve both issues.

Do you need to store toys in this space? Is there no room in the kids' bedrooms or in another play area? If you absolutely must, I'd think about getting a large ottoman/coffee table that has storage inside rather than addiang cabinetry. Like these, perhaps:

GDF Studio Etoney Fabric Storage Ottoman, Light Gray · More Info

Simpli Home Avalon 48" Contemporary Faux Leather Storage Bench in Denim Blue · More Info

You can use these as coffee tables, or use it as a bench under the mirror.