According to the MATLAB manual, when you save a figure using print or by choosing file|save, if you choose the painters renderer and s
If I'm reading that link correctly, not all fonts get substituted. From 'Choosing a Printer Driver':
The table below lists the fonts supported by the MATLAB PostScript and Ghostscript drivers when generated with the Painters renderer (fully vectorized output). This same set of fonts is supported on both Windows and UNIX:
AvantGarde
Helvetica-Narrow
Times-Roman
Bookman
NewCenturySchlbk
ZapfChancery
Courier
Palatino
ZapfDingbats
Helvetica
Symbol
So, if you use one of the above fonts, the output vector-format figure should maintain the correct font. See for example:
list_fonts = listfonts
figure('renderer','painters'),
plot(peaks),
xlabel('this font is Helvetica','fontname','Helvetica','fontsize',24)
set(gcf,'paperpositionmode','auto')
print(gcf,'-depsc2','test1.eps')
Which produces:

So, choose one of the fonts from the list above, and the font will be output correctly. Otherwise, change the font in your presentation to match one of the above fonts.