For anyone who reads Portuguese, here is the article:
TAAG vai apurar caso de funcionário fechado no porão de um avião
To paraphrase the article, his colleagues noticed he was missing after the aircraft took off and the captain was informed. The aircraft diverted to Lisbon and the ramp worker was found in the belly hold and taken to hospital. No mention of his condition.
I wonder if the 777 was overweight when it landed in Lisbon?