Are the advisory fees on broker accounts an investment expense?

[MinhT1]

Yes.

However, on form 8960, miscellaneous investment expenses on line 9c can be deducted only to the extent these items are deductible in Schedule A. As the Tax Cuts and Jobs Act of 2017 has suspended the itemized miscellaneous deduction, these expenses are not deductible on form 8960 either.

Please see these IRS instructions for form 8960, especially on page 19.