The messiah is to be "anointed" and must be versed in the law which mean he would have been alive for a while, and then embarks on his duty by accomplishing the follow:
All Jews would be living in Israel (Isa. 11:12, 27:12-13);
Israel would also be populated by the resurrected souls who died in previous generations (Isa. 26:19);
The Holy Temple would be rebuilt and functioning (Micah 4:1);
There would be world-wide peace (Isa. 2:4, 11:6, Micah 4:3);
and,
The entire world would believe in the G-d of Abraham (Isa. 11:9, 40:5; Zephaniah 3:9).
These things are suppose to be ushered in during the Messianic age. Will he be alive to accomplish all these (considering he's human) or is there any mention of his descendants (if he'll marry) or any other thing to prove he'll be alive till all of these are accomplished?