Adventist teaching: Yes
Biblical teaching: No
Daniel 8:14 is a foundational text to the Seventh-Day Adventist Church. If their interpretation is wrong, their whole system of theology collapses. They claim—using the Day-Year-Principle (DYP)—that the “2300 evenings and mornings” pointed to the year 1844 when Jesus would begin the Investigative Judgment and cleansing a sanctuary in Heaven.
Verse 14 is a response to a question being asked in Daniel 8:13, which is about how long the Wicked Little Horn (who they claim is Papal Rome) of the chapter will do wicked things and then cease. Thus, contextually, the “2300 evenings and mornings” are about the Wicked Little Horn power, not Jesus.
The other major issue is that the Hebrew word “yom” (which means day in Hebrew) is not found in Daniel 8:14. This interpretation is wholly dependent upon the English King James translation. The DYP cannot be utilized in this verse because it requires the use of the word day, hence why no other Historicist group that utilizes the DYP has arrived at this conclusion.
The Adventist Church has known about these issues for many decades (see The Problems in Daniel and Revelation Committee), but because the context doesn’t change, they haven’t been able to come up with a way to not make more problems for themselves. They claim the sanctuary to be cleansed in the passage is the Heavenly Sanctuary which was desecrated by the sin-laden blood that Jesus supposedly took into the Most Holy Place to begin cleansing the sanctuary. At the same time, they will tell you that the Little Horn is representative of Papal Rome and it was Papal Rome that defiled the Heavenly Sanctuary. How that happened, no one knows.
Because 1844 is foundational to their movement, this longstanding problem will forever persist. The cleansing mentioned in the passage is clearly in reference to the earthly sanctuary when it was still standing. This is actually why the Jews celebrate Hanukkah and they never understood the cleansing to be about the Messiah or a sanctuary in Heaven becoming defiled. For more on this, one can also read about the Maccabean Revolt which is when the cleansing of the sanctuary took place.