This mention of the temple in heaven is one of many references to the sanctuary in the book of Revelation. Each of Revelation's seven main sections begins with a scene based on the sanctuary. Let me summarize them briefly.
Revelation 1:12-20. Jesus walks among seven golden lampstands (verses 12-20). He is not in the heavenly sanctuary, but on Patmos (verses 9-12). The lampstands represent the churches on earth (verse 20). So God's church is a temple in its own right (1 Cor. 3:17; 1 Peter 2:1-10).
Revelation 4; 5. Revelation 4 and 5 contain a thorough mix of images from every part and service of the sanctuary. The scene probably represents the inauguration of the sanctuary itself, when every item in the sanctuary was dedicated to God.
Revelation 8:3-5. The focus of this passage is intercession. The prayers of the saints combine with incense to enhance their effectiveness before God.
Revelation 11:19. Here is a view of the Most Holy Place, containing the ark of the covenant. It appears in the context of judgment.
Revelation 15:5-8. In Revelation 15 and 16 the temple empties and is not put into use again. The heavenly sanctuary, inaugurated in Revelation 4 and 5, went through phases of intercession and judgment, and is here shut down. Its services have ceased.
Revelation 19:1-10. We note a total absence of sanctuary furnishings in this text: no building, no censers, no altar, no ark of the covenant, no lampstand. Worship is taking place, just as it does in Revelation 4 and 5, but without any direct reference to the sanctuary and its furnishings.
Revelation 21: 1-8. In Revelation 21:2, 3, the "tabernacle" is actually the New Jerusalem descending to earth. The city is shaped like a cube, just like the Most Holy Place of the sanctuary. God and the Lamb Themselves become the temple of the city.
The book of Revelation displays a completed sanctuary cycle. The cycle begins on earth (Rev. 1) and ends on earth (Rev. 21). Scenes 2-6, on the other hand, focus on the heavenly sanctuary throughout the Christian Era. The sanctuary is inaugurated, goes through phases of intercession and judgment, then is abandoned. When the plan of salvation comes to an end, the sanctuary will no longer be needed.
Lord, help me to take advantage of every provision You have made for my salvation.