The expert was correct in what will be needed to properly apply the general rules to the specific situation.
You are correct that if there was a purchase of furniture or fixtures that the store owner owns (and is not only leasing) that those items would be depreciated in the usual manner for furniture or fixtures including bonus depreciation
and possible section 179 expense election, if not limited by income.
For items that are qualified leasehold improvements of retail property straight line depreciation over 15 years with the 50% bonus available for the year in service may apply.
"Qualified leasehold improvement property. Generally, this is any improvement to an interior part of a building that is nonresidential real property, if all the following requirements are met.
The improvement is made under or according to a lease by the lessee (or any sublessee) or the lessor of that part of the building.
That part of the building is to be occupied exclusively by the lessee (or any sublessee) of that part.
The improvement is placed in service more than 3 years after the date the building was first placed in service by any person.
The improvement is section 1250 property. See chapter 3 in Publication 544, Sales and Other Dispositions of Assets, for the definition of section 1250 property.
However, a qualified leasehold improvement does not include any improvement for which the expenditure is attributable to any of the following.
The enlargement of the building.
Any elevator or escalator.
Any structural component benefiting a common area.
The internal structural framework of the building."
Of course other items including the franchise may be in the total paid and are section 197 intangibles that must be amortized over 180 months.
As you may know inventory is not depreciated but will be part of the cost of goods sold.
Start up costs may or may not be part of this payment.
Hope this gives you a general guide of the various methods to account for the cost. You may be well served to engage a tax professional and provide all the documents and details to properly apply the general rules to the specific situation.
Please ask if you need more information or discussion.