Dan Borges respondeu ao tópico de Felipe Nobre em .NET
Veja se de alguma forma esses tópicos ajudam:
https://social.msdn.microsoft.com/Forums/en-US/1c387f26-49ad-4f82-83d6-6422dcd7cd89/special-characters-displayed-incorrectly-when-compression-disabled-in-local-reportviewer?forum=vsreportcontrols
https://forums.asp.net/t/1333585.aspx?Font+encoding+for+pdf+generated+on+the+fly+using+ReportViewer