Can my silver maple with bark damage and fungus be saved?

What you describe sounds like one of many different types of wood decay fungi. These attack the heartwood, not the sapwood. This is how a tree with massive decay can still have a dense, healthy foliage. Such trees are usually structurally defective. The fact that they are alive and have healthy foliage actually renders them even more of a risk, since there is plenty of weight and wind resistance aloft, and the casual observer doesn't make a distinction between health and structural stability. There is no chemical control, or treatment for such wood-rotting pathogens (although there are successful treatments for various root rots, vascular diseases, and leaf diseases). In certain situations, however, we can help add some years to the tree by promoting good health. This is done by addressing soil nutrition and suppressing other defoliating/damaging diseases and pests. Of course, the tree would have to pass the structural risk assessment and not be recommended for removal, before embarking on such a regimen.