In the sentence you wrote, many thanks is plural, and you should write many thanks go.
Thanks is also used as singular, as shown in the following sentences reported by the Corpus of Contemporary American English, which find 13 sentences containing thanks goes used in academic context.
My deepest thanks goes to the German and US journalists who shared their expertise with me in the context of my fieldwork. [ACAD]
A special thanks goes to Kara Goodson and Jimmie King at PSA Headquarters. [ACAD]
Special thanks goes to the world's exhibitor community for they submitted nearly 2,500 entries (10,000 images) for the judges and ultimately for exhibitions at the Conference in Baltimore. [ACAD]
[...] and a lot of thanks goes to Cory Parker. [NEWS]
A heartfelt thanks goes out to the staff of the Victims Witness Assistance Program. [NEWS]
My heartfelt thanks goes to the police and paramedics for their quick and caring response. [NEWS]