The sentence 'hence he will' is correct and usable in written English.
It is used to draw a conclusion based on evidence previously presented. For example, "John has worked hard on this project, hence he will be capable of completing it on time."
A few months hence, he will receive an Oscar nomination for 12 Years A Slave.
Hence he will delay his Paris sojourn and go first to Dublin, then to Glasgow, Edinburgh & environs.
Hence he will oversee Direct Action, an inefficient, costly policy that aspires to cut emissions and placates his backers who believe climate change is real.
But as with many moves by Mr. Hussein, the end result garnered great populist appeal and hence he will probably have the last word on the fate of the famous ruins.
Mr. Obama will not have the broad mandate the Great Depression handed F.D.R. Hence, he will not have the liberty to press for legislation the way F.D.R. did in launching the New Deal.
Boy George, currently wearing an electronic tag after being found guilty of imprisoning a male escort, has been told by a high court judge that as an attempt to lift a probation service order has failed, the restrictions on his freedom will remain, hence he will not be able to appear on the last-ever series of Celebrity Big Brother.
Hence, he'll have to advocate revision to common-sense morality.
In this step, the individual recognizes the existence of a problem to be solved: he recognizes that he is hungry, that it is dinnertime, and hence that he will need to take some sort of action.
The television set has become merely another used household possession, subject to wear, tear, and breakdown, and he is happy in the realization that hence-forth he will feel free to take it or leave it.
Three thousand years hence, he concludes, historians will say: "The Machine provided a new mind for an old species.
Hence why he'll always see Sam's desire for a normal life as proof of his own inferiority, not of their differing life goals.
