I told by a co-worker that he believed heaven to be empty. He said that those who have died are waiting on judgement and they are in a ‘purgatory-like’ place. I am not sure how to answer this. As far as scripture or some assurance that some have reached heaven.
From scripture, its believed that Enoch and Elijah are in heaven.
Genesis 5:24.
23 The whole lifetime of Enoch was three hundred and sixty-five years.
24 Enoch walked with God,
2 Kings
9 When they had crossed over, Elijah said to Elisha, “Request whatever I might do for you, before I am taken from you.” Elisha answered, “May I receive a double portion of your spirit.”*
10 He replied, “You have asked something that is not easy. Still, if you see me taken up from you, your wish will be granted; otherwise not.”
11 As they walked on still conversing, a fiery chariot and fiery horses came between the two of them, and Elijah went up to heaven in a whirlwind,c
12 and Elisha saw it happen. He cried out, “My father! my father!* Israel’s chariot and steeds!” Then he saw him no longer.
Of course Catholics believe Mary is in heaven too, perhaps Moses.