宾语从句 语法I don't know if ／whether he still lives here after so

答：Does he still live here?
析：我认为after so many years应该是主句：I don't know 的状语.可以改为：
After so many years, I don't know if /whether he still lives here.
过了这么多年之后,我不知道他是不是还住在这里.
语境：我俩是发小,我以前住在这里.我们以前是好友.后来我离开了这里,与他失去了联系.过了多年（比如说30年）,我回到故地,在进这个村之前,我在想：他还住在这里吗?Does he still live here?
我不知道.

if ／whether he still lives here after so many years 是宾语从句，做know的宾语。
你问的是疑问语序哦？ 那就是 Does he still live here after so many years. 是个一般疑问句。

原来的直接引语是个一般疑问句：Does he still live here after so many years?
一般疑问句变为间接引语时用连词if ／whether 引导；而特殊疑问句变为间接引语时用原来的疑问词。

will he still live here after many years?应该是将来时，从你的问题中看

Does he still live here after so many years?