My wife has had green card for 4 years. She was recently furloughed due to Coronavirus shutdowns. Can she file for unemployment benefits and if she does, will USCIS have that as black mark against her for US Citizenship?
She is eligible for unemployment benefits. There will be no adverse effect on her immigration status.
https://www.avvo.com/legal-guides/ugc/public-charge-rule-is-expanded-how-does-this-affect-you-
Eligiblity for unemployment benefits per se is a question of state law, and thus varies by jurisdiction, but as a Lawful Permanent Resident with unrestricted authorization to work in the US, she is likely to be eligible to receive unemployment insurance benefits. Receipt of unemployment benefits will NOT be counted against her as evidence of being likely to become a Public Charge for purposes of her future eligibility for naturalization.