Will chemotherapy help at all with 8.7cm thyroid cancer with mestatic neck disease and spread to nearby lymph nodes?

Thyroid treatment. First line against thyroid cancer is surgery. You need to get all detectable disease out of the neck (the primary tumor and nodal metastases). Radioactive iodine is used to eradicate remaining thyroid and thyroid cancer cells. This can also help with distant mets in lungs/bone/etc. This can be repeated. External beam radiation ; chemo are reserved for cancer that has become dangerous.
Probably. Thyroid cancer is quite responsive to treatment with radio-iodine. Your best source for information on treatment is your oncologist.