I doubt that he could call himself a professional gambler.
The $55K will be added to your income and your AGI. The $50K in losses, as previously noted, can be deducted on Schedule A as an itemized deduction. Since the $50K exceeds your standard deduction, it will generally be to your benefit to itemize. You can include any other itemized deductions - state income taxes and charitable contributions are the two big ones usually (plus property tax but you said you rent).
I think what's probably happening is that there are other things on your tax return that are being impacted by the increase in your AGI (like ACA subsidies, or perhaps the child tax credit).
Note that if you itemize this year and get a state income tax refund, then that state income tax refund will probably be taxable income on your federal return for next year.
Unemployment is taxable in 2021, and you'll probably receive a 1099-G for that from your state.
There is a special provision in the 2021 rules that since your husband received unemployment income, your FPL for ACA subsidy purposes is set at 133% of FPL, which means your ACA subsidies, if you are eligible, should be excellent. Make sure you check the correct boxes for that.
Other than that, the unemployment income and the gambling stuff don't really interact other than the fact that both will add to your income for the year.