I am looking to travel by rail from Lucerne to Strasbourg with an elderly companion. This service has one connection in Basel. There is only 7 minutes to change trains and departure for Strasbourg. Has anyone travelled this route and how "do-able" is it.

You have two possibilities :
travel via Germany and travel direct to France.
travel via Offenburg-Germany : the train leaves +- on the same platform where you arrive in Basel and time is enough.
travel direct to France : you have to walk for 10 minutes and you have 15 min. between trains.

There is frequent regional train service between Lucern and Basel. Taking an earlier train would give you plenty of time to connect with your train to Strasbourg.
Your best bet is as timothy has suggested. You buy a ticket Lucerne to Strasbourg but there is nothing stopping you from doing the leg to Basel earlier. The ticket is valid.

There is also (mostly) hourly regional train service between Basel and Strasbourg, so if you miss your train at Basel, take a later one.

Thanks everyone for your comments. I have checked and yes, I can catch an earlier train into Basel giving us plenty of time to make the connection.

Circulating around Basel station implies some distance from "swiss" to "french" sides, escalators or stairs, and long platforms. Also consider the possible (rare...) customs check.
7 mn is OK if you know the station well, and can move fast!
Considering the risk of a late arrival...there are frequent departures to Strasbourg, and no need to book on local trains.