Assuming it is the WNR834BV2 then no, you can't monitor the byte count. Only the Packet Count, and the bytes within a package vary.
You can however check to see what devices are connecting to it. Details in the Reference Manual
It looks as though it is possible to see the byte count for the modem, but that should be greater than the data count as there are hand-holding bytes going back and forth to the satellite even when you aren't using it. You would need to find out from the router what IP address it had assigned to the modem, then try to access that address through your browser URL bar. I'd expect it to be something between 192.168.1.2 and 192.168.1.254.
My broadband basic info/help site - www.robertos.me.uk
| Domains,website and mail hosting - Tsohost
Connection - Plusnet
UnLim Fibre (FTTC). Sync ~ 55.8/14.5Mbps @ 600m. - BQM
"Where talent is a dwarf, self-esteem is a giant."
- Jean-Antoine Petit-Senn.
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.