Christian Richardson was hit by a pick-up truck as he was leaving a coffee shop, on the island of Koh Samui on April 13.
The 32-year-old, who moved to South East Asia last year to become a Muay Thai fighter, was then airlifted to Bangkok and told he needs to undergo a number of surgical procedures as he had suffered several fractures and lacerations.
His sister Emmy Watson and friend Allison Strahorn have raised more than £29,000 on gofundme so far to cover his medical bills, but set a target of £60,000.
Ms Strahorn said he is bed-bound, while recovering from surgery to repair a broken cheek bone and orbital floor fracture, waiting for a skin graft procedure on his foot and fighting an infection.
She also said the insurance company has refused to cover his mounting medical bills, but the family are seeking legal advice and looking to appeal.
“We don't actually know at this point how long he's going to need to stay in the hospital,” she said.
“A lot of it is going to depend on the skin graft. He's still on a lot of antibiotics and pain relief and he still has a lot of broken bones.
“He's actually kept an amazing fighting spirit throughout the whole thing. He's never given up.
“Even on days when you knew that he was in so much pain, I was just so amazed at his bravery and how he just powered through.”
She added: “We're incredibly grateful that he somehow didn't lose his life in the accident. He's a real friend, he's an amazing guy and he has just touched so many people's lives.
“To get everyone's support, to help us get him whatever care he needs, is just so important.”
Mr Richardson worked at the family business Gillygate Framing in York, before he moved to Thailand nine months ago.
He won his first Muay Thai fight shortly before the motorcycle collision.
You can make a donation on the family's gofundme page.