A weeklong Tanglewood festival celebrating James Taylor has been a boon to the Boston Symphony’s bottom line, and not just because tickets flew out the door. “Instead of being paid for the gig, Taylor will give the symphony $500,000, his earnings after expenses.” Taylor and “his wife, Kim, [who] was a longtime [BSO] staffer and has now been elected to serve as a trustee,” have donated more than $1 million to the BSO in the past few years.