7-day JR Pass

We are a family of 5, with an 8-day trip to Japan. Is it advisable to buy the 7-day JR Pass for Osaka-Kyoto-Nara-Tokyo-Osaka itinerary?

Thanks.

How about leaving Tokyo for a future trip?
7 days JR Pass will pay off the journey from Osaka to/return Tokyo but for a 8 days trip, it is better to just stick to the Kansai area.

The above has a good point - you are cramming in a lot for just 8 days. It would be better to stick to one area, unless you are sure you won't be returning to Japan ever again or for a long while.
For the question though, you would like save more using the japanican ticket instead of the 7 day JR Pass, unless you add more (Himeji, or even just the N'Ex).
https://www.japanican.com/en/special/tours/shinkansen/index.aspx
Even with Nara etc, you'd still come out ahead, and you can take the Nozomi trains, getting you there 30 minutes sooner.

Kyoto (incl Nara)/Tokyo is ok for a introduction trip of 7/8 days. (Note Tokyo rather than Osaka.) The 7-day pass will save a small amount of money.