If I understand correctly, your concern is that the holes in the two sides of the torus aren’t connected by a cylindrical surface, instead you see into the interior of the torus? I’ll assume you have made components of the torus and the cylinders, since otherwise it is much messier. The top of your screen shot reveals you have SketchUp Make, not Pro (please edit your profile, as that info is relevant to the answer), so I’ll give a method that doesn’t use the Pro solids tools.
To create the connecting surface, you need to copy the cylinders into the torus component (select, copy, open the torus for edit, paste in place, explode), intersect them with the torus (select, Intersect Faces with…Selection), and then delete the extra bits. Because they are in the same context, the walls through the hole will remain if you erase carefully. There is a chance of losing tiny faces if the objects are small, in which case you should use “the Dave Method” of scaling up a copy of the component before doing the Intersect Faces with.