The attribution of this widely quoted remark about nuclear war to Khrushchev is disputed in Respectfully Quoted : A Dictionary of Quotations (1989) http://www.bartleby.com/73/1257.html.
In Russia this quote is usually attributed to the translation of Treasure Island by Nikolay Chukovsky: "А те из вас, кто останется в живых, позавидуют мертвым!" ("Those of you who will be still alive will envy the dead", originally: "Them that die'll be the lucky ones"). http://www.chitaem-vmeste.ru/pages/material.php?article=89&
Disputed
No instance of this statement, allegedly in reference to nuclear war, has been found in Khrushchev's writings or documented remarks, as indicated in Respectfully Quoted : A Dictionary of Quotations (1989) http://www.bartleby.com/73/1257.html. Herman Kahn used "the survivors [will] envy the dead" in his 1960 book On Thermonuclear War.