If someone has a vocation the the priesthood, but goes against it and gets married and lives a holy life, will that person go to hell for ignoring the call to the priesthood?
No. A vocation is not a conscription, it is an invitation: You can accept it or reject it, but there are no penalties for declining. Each Catholic, according to his best discernment, must choose the path in life that he believes will lead him to God. For some that may be the priesthood or the consecrated religious life; for many, it may be marriage. Whichever state in life the person chooses, God can give that person the grace to achieve holiness through it.
The story is told of Bd. Frederic Ozanam that a priest with whom he worked on charitable endeavors was distressed because Bd. Frederic had chosen to get married. The priest, during a visit to Rome, complained of this to the Pope and said: “Monsieur Ozanam is falling into the trap [of marriage]!” He asked the Pope to intervene so that Bd. Frederic would pursue the priesthood, as many priests in his local diocese had hoped he would.
The Pope thought about it for a minute and said: “I thought the Christian religion had seven sacraments; not six sacraments and a trap.” By this quip, he was pointing out that marriage is both a sacrament and a legitimate path to holiness.