will the troop build up be successful in afgannstand?

Since we have no military personnel "in afgannstand", nope it will NOT be successful.

Time will tell. Success will be determined by those in charge at the time. Total success is probably not likely in a country such as that. There's too many radicals in that part of the world that want things their way and they're willing to kill to keep it that way.

It'll be no more successful than the troop increases were in Viet Nam

Not likely when it's meant to be part of an exit strategy instead of achieving victory.