My rental condo water leaking damage. Can I claim I paid to my neighbor's $8000 for casualty loss? Can I claim cost to repair my floor for casualty loss?

[Zbucklyo]

Starting in 2018, casualty losses other than those associated with federally declared disasters, are not deductible.

[TomD8]

If this is rental property, should he be able to deduct the cost of "repairs and maintenance" on line 14 of Schedule E?

[Zbucklyo]

Yes, sorry skipped over the rental part.

[TomD8]

Personal casualty and theft losses of an individual sustained in a tax year beginning after 2017 are deductible only to the extent they're attributable to a federally declared disaster.  https://www.irs.gov/pub/irs-pdf/i4684.pdf

If this is rental property, see comments below.