No, SQL server 2005 is not supported in 10.4.1. Below are the supported SQL server versions.
To crosscheck the supported stack, the Product Availability Matrices (PAM) are available online at: https://network.informatica.com/community/informatica-network/product-availability-matrices
As Smitha has mentioned, for 10.4.0 version also same versions of SQL server are supported:
Please close this case thread if your concern is cleared.
As an additional side note, one may come to the idea of connecting from PowerCenter 10.4.1 to SQL Server 2005 via some old ODBC driver.
Don't try that. You can expect this old ODBC driver to not work with PowerCenter 10.4.1 at all.
And even if a connection will be established, you can safely assume (as of my experience) that you will lose data this way.
There's no safe other way but to find a "fully supported" (by both companies) upgrade path for both worlds.