No, every act of piracy does not impact revenue by the current content price
It is important to look at why this claim even exists and who makes it. Firstly, it certainly isn't a strawman. While not every content rights holder who criticizes piracy or talks about lost revenue equates every download with a lost sale, several do currently or have done so..
Claims of copyright infringing downloads equating to a lost sale
This claim that every download is a lost sale seems most commonly attributed to the RIAA. I could not find anyone from the RIAA making such a claim, however I found a judge stating that seemed to be the RIAA's assumption at least at one point.
RIAA’s request
problematically assumes that every illegal download resulted in a lost
sale.
Source: http://www.vawd.uscourts.gov/OPINIONS/JONES/207CR15REST.PDF
Evidence against such claims
There are several reasons why it would seem flawed to consider every download a lost sale:
For example, in the case of software, the pirating of Windows
oeprating system software and Microsoft office products has halped
cement Microsoft's domiance in the PC software inddustry in developing
countries in Asia and Latin America, bringing customers into the fold
that could not afford legal versions of the products. In a recent
example, Microsoft declared amnesty to software pirates in Russian
cyber cafes because it has recognized that (1) under the present
economic conditions in Russia, these businesses could not afford to
pay the “legal” price for the software,...
Source: Piracy as Strategy?: A Reexamination of Product Piracy
It started from small groups of enthusiasts, who had no options for
watching anime other than distributing it illegally. They were even
encouraged to do so, though never officially. Many anime creators were
fully aware of the fan activities in the United States, and although
they could not recognize them as legal, they condoned them
Source: Piracy or productivity: unlawful practices in
anime fansubbing
- People who download because they won't purchase a product with DRM
The most often used estimate for the rate of downloads which can be equated to a lost sale seems to be 20%:
A number of academic studies have attempted to estimate the impact
that file sharing has had on sound recording sales. The specific
estimate of 20% is taken from Pietz, M. and Waelbroeck, P., The Effect
of Internet Piracy on Music Sales: Cross Section Evidence , Review of
Economic Research on Copyright Issues, 2004, vol. 1(2), pp 78.
Source: The True Cost of Sound Recording Piracy to the U.S. Economy
The actual impact of piracy on content revenue
In addition to the reasons and studies showing that not every download should be considered a lost sale, there have been studies showing that piracy impacts the content industries to a far less extent than is generally claimed and that in some instance can be beneficial.
- A report from the IFPI in 2009 estimates that 95% of music downloads are illegal, and that only 10% of that 95% can be considered a lost sale.
Source: DIGITAL MUSIC REPORT 2009
- A report showing that the music industry lost substantially less than estimated
However, the impact of piracy on CD sales was considerably smaller
than industry estimates. Further, we estimated that, accounting for
both demand losses and price adjustments, the industry lost no more
than 6.6% of revenue to piracy.
Source: Piracy and the Legitimate Demand for Recorded Music
- A study of French college students found that piracy had a positive effect
Surprisingly, approximately one third of the pirates declared that
watching pirated movies increased their demand for films (for
instance, it led them to rent or purchase videos that they would not
have rented or purchased otherwise). Using regressions analysis, we
find no impact of piracy on theater attendance, and a strong impact on
video rentals and purchases. However, movie piracy has no impact on
video rentals for respondents who use pre-paid pricing schemes at
video-stores.
Source: Piracy and the Demand for Films: Analysis of Piracy Behavior in French Universities
Conclusion
All in all, there does not seem to be sufficient evidence to support the claim that each copyright infringing download hurts profit by the same margin as the price of that content. The studies above show that while copyright infringement can have an effect on revenue it is far less than generally claimed and certainly less than a 1:1 ratio of downloads to lost sales. The affect of piracy on revenue may be different for different industries (music, film etc) but in no case is the impact on revenue anywhere near a 1:1 ratio.
Given that piracy can be shown to be beneficial in some cases that would also disprove the titular idea. The only people or organizations who seem to continue to make the claim are those with an agenda who rely on distorted figures (e.g. the BSA report referenced above) or those who argue from an emotional or moral standpoint.
We have more than enough data to conclusively say, no, every act of piracy does not impact revenue by the current content price.