I looked through some of the engine code and it appears that this vector only exists on the executable belonging to the local player controller. I do not think this value gets replicated to the server.
The acceleration on the server is affected by this input vector. Their direction are usually the same if there is no other values operating on it.
For my problem all I needed was the direction. I think this should work, but it it does not I will reopen this question since the input vector is definitely the value I will truly need.