If I don’t have a wi-fi connection to my Roku tv can I still view or stream what is on my iOS device using the data and not the hotspot?

Wireless streaming from an iOS device to a Roku TV with AirPlay support, requires a Wi-Fi connection and both devices to be connected that same home network.

Streaming content form the internet requires that the home network is connected to the internet.

Streaming content of local files (your own recorded videos) does not require internet access.

Streaming downloaded content from Apple does require an internet connection for authentication.

Using a the hotspot from your phone should suffice for Wi-Fi access with internet.

using the data and not the hotspot?

That distinction does not exist.