This was, of course, a question that was put to the Lord Jesus (Luke 13:23).  We would do well to take his response to heart: it matters little whether they are few or many, if you are not among that number.

Still, some things can be said about this subject.

The question is faced up to squarely by the Puritan Christopher Love, even though he found his conclusion to be ‘one of the most dismal doctrines’ a pastor could preach.  Love’s views are summarised by Beeke and Jones , A Puritan Theology: Doctrine for Life, p834:-

1. most will go to hell because most do not look to Christ to deliver them from such torment—whether Jews, Muslims, heathen, or Papists.
2. even among those who “profess Jesus Christ,” many are called, but few chosen (Matt. 22:14), as most are “either profane in life, or hypocrites in heart.”
3. when you see such descriptions of men as grasshoppers (Jer. 46:23), bees (Ps. 118:12), briars and thorns (Isa. 10:17), mire and dirt (Isa. 57:20), stones (Matt. 13:5), and wooden vessels (2 Tim. 2:20), you realize that they were ordained for destruction as “the greatest number of men in the world.”
4. most live and die in the very sins that lead people to hell, as they die without repentance in “a course of sin” seeking pleasures, whores, and lusts, while few “seek after Jesus Christ.”
5. when you consider all of the different men in the world and the greatest of them, you will find that most “are ordained for hell, this place of torment.”
6. this is the testimony of Scriptures as it speaks of the “broad” way of destruction (Matt. 7:13), the “strait” gate that few will enter (Luke 13:24), the “little” flock of God (Luke 12:32), and the “remnant” of Jews that shall be saved (Rom. 9:27).

On the other hand, a number of reformed scholars have entertained the possibility that many more people will be saved than will be lost:

‘We have reason to believe that the number of the finally lost in comparison with the whole number of the saved will be very inconsiderable.’ (Charles Hodge, Systematic Theology, Vol 3, p879)

Warfield (Hastings Dictionary of the Bible, Vol 4, p63) calls the lost ‘a relatively insignificant body.’

J.C. Ryle (in a comment on Lk 13:23) offers a few reasons for supporting this view: ‘When all the infants who die without knowing good from evil, and all the “nations of the saved,” who shall be converted after the calling in of the Jews, are added to the ranks of God’s elect under the present dispensation, they shall be a multitude that no man can number. They will probably far exceed in number those who are lost.’

(The above comment was first published in book form in 1858.  It is curious that this esteemed author had taken the opposite view in an 1852 sermon entitled ‘Shall you be saved?’, and reproduced this in his 1877 book Old Paths.  Ryle states: ‘According to the Bible, few will be saved’, and expends much energy in explaining and defending this view.)

The distinguished New Testament scholar F. F. Bruce offers a brief discussion in Answers to Questions (p197f).  He cites Enoch Powell as thinking that salvation ‘will not be for all, not even for the majority.’  Why?  ‘Ignorance, incapacity, perversity, the sheer human propensity to error are sufficient to ensure a high failure rate.’  Bruce comments, drily, that ‘they are sufficient, indeed, to ensure a 100 per cent failure rate, but for the grace of God.  One the grace of God begins to operate, however, the situation is transformed.’  Bruce cites Rom 5:15,19, where Paul teaches that God’s grace in Christ has abounded for ‘the many’.  This, says, Bruce, cannot mean a minority, for, as Calvin puts it, ‘if Adam’s fall had the effect of producing the ruin of many, the grace of God is much more efficacious in benefiting many, since admittedly Christ is much more powerful to save that Adam was to ruin.’