Gusev signed a one-year deal with KHL club SKA St. Petersburg, KHL Insider Aivis Kalnis reports.
Gusev was released from his professional tryout with the Maple Leafs on Tuesday.
Gusev agreed to a professional tryout agreement with Toronto on Friday, per CapFriendly.
Gusev scored a goal on four shots in Saturday's 5-4 win over the Blackhawks.
Gusev is expected to make his Panthers debut in Thursday's game versus the Lightning.
Gusev signed with the Panthers on Sunday, Pierre LeBrun of The Athletic reports.
Gusev was placed on unconditional waivers for the purpose of terminating his contract Friday, Sportsnet's Chris Johnston reports.
Gusev was assigned to New Jersey's taxi squad after clearing waivers Friday, Mike Morreale of NHL.com reports.
Gusev had the primary assist on New Jersey's only goal in Tuesday's 2-1 loss to the Islanders.
Gusev scored his second goal of the season in Tuesday's 4-1 loss to the Sabres.