It depends upon the kind of Christian.
A survey by Faith Matters in 2007 (cited in American Grace: How Religion Divides and Unites Us, by Robert D. Putnam and David E. Campbell, 2010) found that
98% of Mormons believe that people “not of my faith, including non-Christians, can go to heaven.”
Other non-Jews were less convinced.
Only 83% of Catholics believe it.
Only 79% of mainline Protestants.
Only 62% of black Protestants and
Only 54% of evangelical Protestants.