I'm more of a Windows Server guy then Linux, but assuming the underlying architecture of the Tableau Server on Linux is similar to the Windows environment, I do not believe so. The extract refresh job is being run by a backgrounder process, which is single-threaded. The Backgrounder is a CPU-intensive process, but since it's single-threaded, another CPU core isn't going to help. The backgrounder isn't very memory-intensive, so adding more memory likely won't work ether. I'd suggest trying to optimize the extract to reduce the amount of data refreshed rather than throwing more resources at it.
I found this backgrounder dashboard that might help diagnose issues: Managing Backgrounder and Extract Refreshes
And this article talks more about the processes of Tableau Server: Tableau Server Processes
This article talks about optimizing extracts: Optimize for Extracts
Hope this helps!