Is there a way to get Helvetica fonts to resolve on CentOs? We are evaluating Prince and can't seem to get good results in a linux environment.

I've installed the msttcorefonts rpm per the font documentation.

Here's the section of the debug logging where fonts are being searched:

prince: Converting document...
prince: debug: pack
prince: debug: font request: Helvetica
prince: debug: font scan: Helvetica
prince: debug: font scan: Helvetica, 0 matches
prince: debug: font scan: Times New Roman
prince: debug: font scan: Times New Roman, 4 matches
prince: debug: font scan: DejaVu Serif
prince: debug: font scan: DejaVu Serif, 0 matches
prince: debug: font scan: OpenSymbol
prince: debug: font scan: OpenSymbol, 0 matches
prince: debug: font scan: AR PL UMing CN
prince: debug: font scan: AR PL UMing CN, 0 matches
prince: debug: font scan: AR PL SungtiL GB
prince: debug: font scan: AR PL SungtiL GB, 0 matches
prince: debug: font scan: Lohit Hindi
prince: debug: font scan: Lohit Hindi, 0 matches
prince: debug: font scan: Ani
prince: debug: font scan: Ani, 0 matches
prince: debug: font scan: Mukti Narrow
prince: debug: font scan: Mukti Narrow, 0 matches
prince: debug: font scan: Lohit Punjabi
prince: debug: font scan: Lohit Punjabi, 0 matches
prince: debug: font scan: Lohit Gujarati
prince: debug: font scan: Lohit Gujarati, 0 matches
prince: debug: font scan: Lohit Tamil
prince: debug: font scan: Lohit Tamil, 0 matches
prince: debug: font scan: Lohit Telugu
prince: debug: font scan: Lohit Telugu, 0 matches
prince: debug: font scan: Lohit Kannada
prince: debug: font scan: Lohit Kannada, 0 matches
prince: debug: font scan: MalOtf
prince: debug: font scan: MalOtf, 0 matches
prince: debug: font scan: Lohit Oriya
prince: debug: font scan: Lohit Oriya, 0 matches
prince: debug: font request: bold Helvetica
prince: used font: Times New Roman, Bold
prince: used font: Times New Roman, Regular
prince: Resolving cross-references...
prince: debug: pack

Any guidance would be appreciated.

The Microsoft Core Fonts package does not include Helvetica, only Arial, which is the standard Helvetica-like font on Windows. There are other Helvetica-like fonts, such as DejaVu Sans, or the Red Hat Liberation fonts, but if you want the real Helvetica you actually need to buy it.