I have a Japanese Maple about 7-8 ft. tall that is at least 40 years old. This winter was hard on most of the small trees in my yard having a late 12 inches of snow after a warm spell. the maple is a "feather-leaf" type and has been very healthy all its life but now the leaves are sparse and the crown has no leaves. The leaves on it are healthy, but the tree is looking sad. How long does a tree of this type live and should I expect it to recover?
Not sure what you mean by 'feather-leaf' but you may be referring to a dissectum variety. It takes about 50 years for japanese acers to reach full maturity, and many survive for up to 100 years, but it varies enormously depending on environmental conditions, see here https://www.hunker.com/12535698/how-many-years-can-a-japanese-maple-live