可不可以说I have no seen him for a long time

不能,应该把NO变为NOT
No 是个形容词,等于not a或 not any.eg:There are no students in the classroom.=There are not any students.
而not是个副词,eg:I am not happy today. No I am not.
no,not
这两个词在词义和使用场合上都有所不同.
No可以作副词,也可以作名词和形容词；not只能用作副词
Not可用于
（一）修饰动词：
I do not know any of them．
这些人我一个都不认识.
（二）修饰形容词：
It's not cold today．
今天天气不冷.
（三）修饰不定冠词：
Three decades ago not a year passed without a number of people falling victims to hunger here．
三十年前,这里每年都有不少人死于饥荒.
（四）修饰副词：
Not seldom did I go to Victoria Park while I stayed in Causeway Bay．
我住在铜锣湾期间常到维多利亚公园去.