The IRS has come out with Revenue Ruling 2020-27, which gives us some direction on how to treat the PPP loan and the related expenses.
Lets look at each separately.
If your business received the PPP loan and it is forgiven, that money is considered non-taxable income.
However, the expenses that your business listed to qualify for forgiveness (payroll, utilities, etc) are not deductible in 2020.
Revenue Ruling 2020-27 clarifies that these 2020 expenses that were used to apply for forgiveness are not deductible, even if the PPP is not forgiven until 2021, as long as you reasonably expect the PPP to be forgiven.
This is the way that the law currently stands. There is some talk in Congress about changing the law and making these expenses deductible, but as of this writing, that is still just talk.