We know Nikki was buried alive as her eyes flew open. However Paulo may have been dead already at the time of burying. He was in the jungle, paralyzed by one spider bite. Then more spiders came. Nikki was only bitten by one, as she then started running away. But Paulo could not move, so with all of those spiders crawling around, perhaps several of them bit Paulo. Would multiple spider bites have killed him? Or would they just have paralyzed him longer? Have we jumped to conclusions that just because we saw Nikki was still alive, that it means Paulo was still alive too?

I dont know about that one. I say Paulo was paralyzed too, since he seemed to be having flashbacks along with Nikki. Maybe he was unable to move for a longer period due to the location of the spider bite on his body?

I'd say the intention was that they were both alive, there's no indication otherwise.