Trump will accept the Saudi denials. Per this CNN article, Trump said “As of this moment, they deny it and they deny it vehemently. Could it be them? Yes.” He said he will do something if it is proven the Saudis killed Khashoggi but he will never be convinced they did it.
The first part of the quote doesn’t sound much different from his acceptance of Putin’s denial of election interference.
If there are tapes, he will claim they could be edited or fake just like he did with the Lester Holt interview and the Access Hollywood tapes.
Trump is more concerned about money (his family’s and government deals) than morality.