Can you contract hiv virus by sharing thesame toothbrush with an infected person?

Theoretically, Yes: But in practice it is highly unlikely. Hiv can live only seconds outside the body & with rinsing, drying, toothpaste, etc. Would normally be killed before being transferred. Still, you should never share a toothbrush with anyone - hiv+ or otherwise - you can transmit decay as well as other diseases like colds, flu etc.

Yes: Hiv is a blood transmitted virus and lives on surfaces for 5-10 days so brushing gums that bleed can transmit the host virus with many brushings is rare but can happen.

Very unlikely: Fortunately, the viability of HIV is very short lived outside of the body and is not contagious once exposed to air and surfaces that dry. There would be some minimal risk if the brush was used immediately after an infected person brushed with it by another. Virtually little to no risk if there was some significant time.